Teacher Misconceptions
Content
Common Misinformation among Earth Science Teachers
There has been a great deal of research into student misconceptions in the field of Earth science. But misinformation and surprising differences of opinion also exist in books and even among relatively well-educated geoscience instructors. Many misconceptions are based on valid observations or application of correct principles, but without enough depth of knowledge to understand the limitations of these principles. Some prime examples are given in this paper. Some of these misconceptions have resulted in errors or incorrect innuendoes in New York State Regents exam items either because of errors in the state core (syllabus) or the incomplete background of teachers on the test committees. It is unfortunate that students could be penalized because their knowledge is more current or more complete than the professionals who write and review test items. This is not an article about student misconceptions or teaching methods to dispel them. Many people have done research in that field and there are many articles and books about this important issue in science education. I am looking specifically at teacher misinformation in the mainstream of our field. It is my interest to identify the specifics of this problem. I leave it to others to explore ways to correct the problem. Nor am I trying to nit pick. While many of these issues go well beyond the level of understanding that we would expect students to learn, these matters can lead teachers to convey information that is known to be incorrect. But it's important to keep in mind that even knowing the same "facts" (as we best understand them) different people will still make different rational decisions. Some of these issues are not as "black and white" as some people would have us believe. For example, an atom has some features in common with the solar system. The "solar system" model of the atom has severe limitations, but this model may be useful to a very young student who would certainly not be expected to fathom quantum energy levels. (It's not clear how well our best scientists understand quantum issues, or, if quantum is, in fact, "understandable" on a human level.) So both scientists and educators use conceptual models that are clearly limited. Furthermore, it seems to me that educators are justified in being a little more lose than scientists. I see four levels of dealing with these issues. 1) Understanding that there is controversy. 2) Understanding the nature of the controversy. 3) Consistency. 4) Collaborative or scientific resolution. My goal in this paper is bring the reader to the second level with regard to these specific issues. I've tried to be fair and accurate, but I would appreciate hearing from anyone who differs with my statements or who can lend further insights.
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Thomas McGuire
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I thank those who have contributed to this listing. Many ideas came from discussions on the New York State secondary Earth science listserv based at SUNY Oneonta. <http://external.oneonta.edu/mentor> I've tried to credit those who initiated discussion about a particular misconception. But the selection of misconceptions and any errors are my own. Thomas McGuire [email protected] (Mr. McGuire (BA, MAT) is a retired science chairperson at Briarcliff High School in suburban New York and the author of several Earth science books with Amsco School Publications of New York. He now resides in Cave Creek, Arizona) ***************************************************************** Geoscience Content Misconceptions 1. Convection drives tectonic plate motions. Measurements show that the speed of a plate is generally a function of the age of the subducting lithosphere at the trench. As subduction zones got older, subduction motion generally speeds up. If motion were driven by mantle convection we would expect plate speeds to be more constant. So it looks like plates are pulled progressively faster by the force of the descending slab. It now appears plates drive the horizontal components of convection more than convection drives the plates. (Tom McGuire) ********************* 1.Isostacy is the key to the subduction. 2. Flexural bending (rigid behavior of the lithosphere), as well as the gravitation force, are components of a subduction boundary. Sometimes flexural bulges (normal faults) occur ahead of the trench 3. Partial melting of the mantle (not the slab) occurs due to dewatering of the slab. The solidus of peridotite is thus lowered. I have yet to see this correctly represented in a textbook. Chris Imperial Lansingburgh High School [email protected] 2. Winds drive ocean surface currents. In fact, major ocean currents are driven by internal convection caused by differences in salinity and temperature. Flow directions are strongly influenced by the Coriolis effect.
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They just happen to line up with the prevailing winds in many locations. (Mike McDonnell) 3. Streams generally flow slower as they flow down hill. Streams usually have a concave profile, becoming less steep as they flow down hill. But the increase in water volume usually dominates over the decrease in slope. So large rivers tend to have a smooth, laminar flow that is actually generally faster than smaller streams. (Tom McGuire) 4. Seismic waves speed up with depth due to an increase in rock density with depth. Seismic wave speeds increase with increasing rigidity. The increased density factor would actually cause seismic waves to slow down. The energy waves generally travel faster with depth due to an even faster increase in rigidity/elasticity of rocks with depth. The term "plastic mantle" may be misleading us to think that rock gets more "mushy" as we look deeper into Earth. In fact, the hot rock within Earth is generally very rigid. (There is, however, a "low velocity" zone in the upper mantle (asthenosphere): where velocities of both P and S waves slow down.) (Marion Weaver & Tom McGuire) 5. Large crystals in igneous rock are primarily a result of slow cooling. If you look at pegmatites and fine-grained intrusive rocks it's clear that there's more going on here. The water content of magma is a major contributor to crystal size. Furthermore, rapid cooling of basaltic rocks does not usually make obsidian. For example, the lava flows in Hawaii are not obsidian. (Most obsidian is actually felsic in composition in spite of its dark color.) But it's still true that rocks that cool slowly do tend to have larger crystals if (!) the composition of the magma is the same. (Tom McGuire) 6. Air holds water vapor. Air doesn't "hold" water vapor. It's not like a sponge or a bucket holding water. Gases exist in the atmosphere independently. The amount of water vapor in the atmosphere is a function of its temperature, but it would be pretty much the same whether the other gases are present or not. If Earth had no atmosphere at all (a vacuum) and a pan of water were set outside, the water could still evaporate, even though there would not be any air to "hold" it. It's usually better to say that a larger amount of water vapor can exist in the atmosphere when it's warm and stay away from the word "hold." However, students often find it easier to understand relative humidity if they think about "how much moisture the air is holding, compared with what the air can hold." It's not uncommon to use simplifications that are not technically correct. This one is especially attractive as a teaching/understanding tool. In my opinion, it's acceptable to use the "h" word, but helpful if the teacher understands the limitations of this usage. To me, this is not an issue of being right or being wrong. When to use simplifications is an important issue both in science and in science education. If we approach these issues
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with an understanding of options and limitations, and an open mind, we can then make informed decisions. (Tom McGuire) 7. Seismologists measure earthquakes with the Richter scale. The actual (original) Richter scale is no longer in use because it only applied only to California events measured with a now outmoded mechanical seismometer. Furthermore, the true Richter scale topped out at about magnitude 8. Several scales are now used that are also log scales and dove tail with the Richter scale quite well. Currently, the moment magnitude, or Kanamore scale, is popular because it's a good measure of energy release in a seismic event. But it's arrived at by methods far more involved than Richter used. But the news media still like to call the modern scales "Richter" in honor of the legendary geophysicist who devised it and to avoid confusing the public. The term "magnitude" is probably more accurate. Some teachers may think that the Richter scale has replaced the Mercalli (intensity) scale. However, the Modified Mercalli scale is widely used by seismologists to map the details of seismic shaking in localized areas where there are few seismometers and detailed mapping is impossible using instruments. For example, Mercalli mapping clearly shows the increased shaking in locations on deep sediments. (The low-density cover often accentuates the shaking.) (Tom McGuire) 8. Pressure is necessary to form sedimentary rocks. Some people probably conflate pressure and compaction. (Unfortunately, many of them also go on to expound, “If pressure is needed, then that must mean elevated heat is present as well, so sedimentary rocks form from heat and pressure.”) In a recent edition of The Science Teacher, there is an article in which the author states (Jim's paraphrasing) that sedimentary rocks form after millions of years of pressure. While this is often true, it is certainly not a necessity. Clearly evaporites such as rock salt form without pressure and many other sedimentary rocks can also form right at the surface. (Jim Ebert) 9. Due to the Coriolis effect, winds curve to the right in the Northern Hemisphere. This is a simplifications that can be confusing. Some people have difficulty with it, as the winds around a cyclone curve left. A good way to think about this is to consider that the winds start to blow from the high straight across the pressure gradient toward the center of the low. They start to curve right. But if they continued to curve right they would blow away from the low pressure region. So they must then curve left to continue to circle into the low. Although the Coriolis effect pushes them to the right, the pressure gradient is stronger so they curve left (the "wrong" way, so to speak) as they circulate counterclockwise into a low Of course it's all reversed in the Southern Hemisphere.
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Thomas McGuire
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A related misconception is that the Coriolis effect is the "Coriolis force." In fact, it's not a force at all. It's just inertia tending to make the winds move in a straight line as we observe them on a spinning planet. We're really doing the curved motion along with Earth as the winds "try" to go straight. (Sharon Miller) 10. Wind is the dominant agent of erosion in desert regions. When some people think of deserts they envision drifting sand dunes. But most deserts locations are rocky with scattered plant cover. The majority of erosion in desert areas is caused by strong thunderstorms that are especially common in summer monsoons, which occur, among other places, in the American southwest in midsummer. Because of incomplete vegetative cover, desert areas of the United States actually experience more water caused erosion than most places along the humid eastern seaboard. (Tom McGuire) 11. Boiling is the same as vaporization. Actually, vaporization includes both boiling and evaporation. Boiling occurs at 100°C under normal Earth atmospheric conditions. (It's very dependent on upon vapor pressure.) At the boiling temperature most of the molecules in a liquid have enough energy to escape as a gas. But even well below the boiling temperature, some molecules have enough energy to escape from the liquid. (Remember that temperature is a measure of the average kinetic energy of molecules. Some molecules have more energy than others.) Evaporation allows only the most energetic molecules to escape; thus reducing the average energy of molecules left behind in the liquid. That's why evaporations is such an effective cooling process. It's also useful to understand that even at the dewpoint (100% humidity) evaporation is still taking place. It's just in equilibrium with condensation. So there is no net evaporation at the dewpoint, even though both processes are still taking place. (Steve Kluge) 12. Heat and temperature are the same. They are related, but not the same. Heat is the total energy of molecular motion/vibration in an object. It depends upon the mass of the object. But temperature is a measure of the average energy of the motion/vibration of molecules. The temperature of matter does not depend upon the mass. A teacup of hot water may have the same temperature as a bathtub of hot water. But they're very different in how much heat energy they have. (Fred Welfare) 13. Objects at 0°Kelvin have no energy. They still have potential energy. For example, the electrons occupy measurable energy levels. The substance may still be able to enter exothermic chemical reactions such as combustion/oxidation. The object may be able to fall toward Earth to yield energy. The whole object may have kinetic energy in the form of its relative motion. We therefore need to define absolute zero as the temperature at which no kinetic heat energy can be extracted or given off, but this is not a temperature at which the molecules have no energy. (Mark Heilbrunn)
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14. A liquid molecule has less energy than a gas molecule. A single molecule can't be a liquid or a solid. It's the association of molecules that make a solid, liquid or gas. I suppose a single molecule could be considered a gas, but it's better to talk about an aggregate of molecules as a state of matter. The statement in bold text above should probably be revised to read, "Molecules in a liquid...." (Steve Kluge) 15. Substances with a high specific heat absorb or release energy quickly. This statement confuses conductivity with specific heat. "How quickly" depends heavily on conductivity. (Specific heat probably does have some influence.) But the specific heat is determined by how much energy can be released or absorbed by a given mass and a given temperature difference. Metals generally have a high conductivity, but a low specific heat. In general, specific heat determines how much energy is exchanged while conductivity determines how quickly the energy is exchanged. (Tom McGuire) 16. The greatest possible relative humidity is 100%. Air in the upper atmosphere commonly falls in temperature below the dewpoint. It there are no surfaces or condensation nuclei for molecules to condense onto, air can become supersaturated and the humidity climbs above 100%. That's the reason for of "con trails" behind jets. Water deposits or condenses from supersaturated air onto the jet exhaust particles. Then the ice crystals or droplets disperse and become invisible. They're probably not evaporating. They're just becoming too thin and spread out to remain visible to us. The term "vapor trail" is unfortunate because water vapor is invisible. A "vapor trail" is really a cloud of ice particles or water droplets formed on jet exhaust particles. (Tom McGuire) 17. A magnitude 8 earthquake releases ten times as much energy a magnitude 7 event. The Richter scale was established so that each step of magnitude is ten times the amplitude (distance) of ground shaking. But due to the increasing energy in low frequency waves, the extended length of time of shaking for larger events as well as geometric considerations, the energy release is about 32 times for each step. So a magnitude 5 earthquake actually releases about 32 as much energy as a magnitude 4 seismic event. Furthermore, that energy ratio remains the same from step to step. (Tom McGuire) 18. Life on Earth has developed in response to the physical environment. This is true, but there's another side of this. Earth's physical environment has also developed in response to life. For example, the oxygen content of Earth's atmosphere became free oxygen by life processes. If it were not for photosynthesis, Earth's atmosphere would be very different, more like the atmospheres of Venus and Mars. This is a central idea of James Lovelock's Gaia theory. The physical environment affects the evolution of life and living things also have a major effect the development of the physical environment. Lovelock even carries Gaia to the point of considering our planet a
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Thomas McGuire
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giant living organism. He considers the atmosphere, oceans and geosphere as organs of this organism. But for most scientists, that's carrying a creative idea too far. Most think it better to limit the Gaia idea to the coupling of evolution of the organic and physical parts of the planet. (Tom McGuire & Jim Ebert) 19. The origin of the oceans is primarily from gases trapped in Earth's original core and expelled by volcanoes. The primary source of water to form Earth's oceans is not settled, in spite of a statement in the NYS Core Guide (1.2g) that mentions only outgassing. Precipitation from Earth's early atmosphere as well as water from collisions of comets have also been suggested as the primary source of the water. In spite of considerable debate and research, at this point there is no consensus about how scientists can select one theory over another. (Tom McGuire) 20. The largest earthquakes occur only near plate boundaries. While there are more seismic events where tectonic plates meet, earthquakes within the interiors of plates can be very large. The size (energy release) of an earthquake depends upon the ability of the rocks to hold stress (force) and strain (bending) before they break. The New Madrid, Missouri events of 1811-1812 were among the largest earthquakes ever known in the United States. The rocks are not as fractured within the plates as they are at the plate boundaries. So intra-plate events, although less common, might actually become larger than plate boundary events. Furthermore, they generally transmit their energy farther (larger felt/damage area) than plate boundary events. (Tom McGuire) 21. The length of the day is exactly 12 hours on the equinox. This isn't quite true in spite of what we have learned or what we teach about the equinoxes. There are a number of reasons. (1) The sun has a visible diameter, so we can see its upper portions both before its center reaches the eastern horizon and after the center point dips below the western horizon. (This effect is lengthened for observers at higher latitudes north and south where the sun has a slanted path thorough the sky and the sun takes longer to drop completely below the horizon.) (2) Earth's atmosphere refracts rays of sunlight. We actually see the sun in the morning before we cold see it if Earth had no atmosphere, and we also see it longer in the evening because of this bending of light rays. (3) The daylight period is not symmetrical around local solar noon (sun transit) so the day is not lengthened by equal amounts in the morning and evening. (4) In addition, changing atmospheric properties cause the amount of refraction to change from day to day. In spite of its name equinox, this time of the year is not defined as a time of equal day and night. Rather, it's more precise to say that the seasons change at the time the sun is exactly above Earth's equator. This can occur at any time of day. Therefore, (5) the length of daylight on the spring and fall equinoxes is unlikely to be exactly the same. If the sun crosses the projection of the equator in the sky closer to our local noon on both days, the day length is more like to be the same at the spring and fall equinoxes. This time of the transit of the equator can either lengthen or shorten the amount of daylight on the two equinoxes making the daylight periods unequal. There is a good explanation of
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Thomas McGuire
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these issues at two web sites, < http://www.analemma.com/Pages/framesPage.html> and http://www.bedford.k12.ny.us/flhs/science/sunrise.html. Of course, all this detail would be pretty tough to teach to young students. Perhaps it's best to just to mention #1 and to say that there are other reasons the above statement is not quite true. (Steve Kluge) A related misconception is that the sun rises perpendicular to the horizon. (Jim Lehmann) 22. The sun is overhead at noon. There are several problems here. The noon sun can not be at the zenith (straight overhead) for any observer on Earth unless the observe is located at a latitude between the tropics of Cancer and Capricorn, and the latitude where the non sun is at the zenith changes through the year. The second issue is clock noon and solar noon. Solar noon is the time the sun crosses the meridian of the sky. (The meridian is an imaginary line through the sky connecting the horizon points of due north and due south.) The precise time of solar noon changes continuously as the observer moves east or west. To keep our lives synchronized with those who live near us, we set our clocks to the same time as other clocks within our hourly time zone. Therefore the sun actually crosses the meridian as much as half an hour before or after noon. A third factor is the speed of Earth in its orbit, which causes the sun to be as little ahead or behind schedule depending on the time of year. The tilt of Earth's axis also contributes to this time difference because the sun gets a little behind schedule when its apparent motion is not parallel to Earth's equator. You can get more details if you investigate the analemma curve, which is the symbol that looks like a figure 8 printed on some globe maps. It's also known as the equation of time. See the two web sites in the item above. (Steve Kluge) 23. The major reason solar time and clock time do not progress at the same speed is the eccentricity of Earth's orbit. This error evolved from the 1970 New York Regents Earth Science syllabus. The time from solar noon to the next solar noon actually varies in an annual cycle. These factor adds up for months causing clock time and solar time to differ by as much as 15 minutes before the two gradually come back together in an annual cycle. While Earth's orbital eccentricity is the only contributing factor stated in the 1970 Regents Earth Science syllabus, the more important reason is actually Earth's tilt of 23 1/2°. The web site below shows how the two factors (elliptical orbit and tilt of axis) add up to the total discrepancy between solar time and clock time. To understand this, visit the following web site. http://www.analemma.com/Pages/framesPage.html. Then click on the tab for "summation effect." A graph there shows how the two effect are added together and their relative contributions to the total discrepancy. In addition to the text in the web site, Strahler's "The Earth Sciences" (1963) also has an excellent explanation for the time difference in chapter 3:" Time." (Steve Kluge) 24. Pluto is the outermost planet. Pluto's obit is eccentric enough that it spends pat of the time closer to the sun than Neptune. Therefore, at times, Neptune is farther from the sun and Pluto. Another problem with this statement is defining what a planet is. In general, a planet seems to be a major
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Thomas McGuire
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satellite of the sun or another star. But Pluto doesn't fit in. Unlike the other outer planets it's a relatively small, rocky object. Some astronomers have suggested Pluto is really a moon of another planet that got bumped or pulled out of place. A similar problem exists in defining a moon. Is there a lower limit to the size of a natural satellite of a planet that helps define a moon? The rings of the gas giants are actually composed of solid particles in orbit. Are they not considered moons because they orbit in rings or are they excluded because they are too small? As of March 2003 the identified moons of Jupiter totaled 52 and the number is still rising. I think we can identify these issues, but astronomers will need to solve them. For now, most astronomers seem to feel that Pluto is a planet, if only for reason is tradition. (Tom McGuire) 25. A radiometer spins because gas molecules bounce off the hotter black side of the vanes. Perhaps you have seen these devices that look like light bulbs with a wind vane inside. When light strikes them, the vanes turn. I've heard and seen some people state that it's the pressure of light photons that drive the motion. But the photon pressure theory would drive the motion in direction opposite to what we actually observe. The bold statement above is the explanation many of us learned from generally good scientific sources. It now appears that both are wrong. What actually happens is that at the edge of the paddles the warm gas molecules meet the cold gas molecules from the lighter side of the paddle, so molecules start creeping round the edge from the paddles from the cold to the warm area. This rapid flow of gas causes the paddles to move in the opposite direction, making it look as if there is pressure being exerted on the black side. In other words, it's the gas flowing around the edges of the vanes the drives the radiometer, not molecular collisions along the faces. (Tom McGuire)
<http://www.bbc.co.uk/science/scienceshack/backcat/adamexp/wlradiometer.shtm l>
26. The changing distance between Earth and the sun causes the seasons. This is more common as a student misconception than a misunderstanding by teachers. But there's a good way to attack this misconception. Earth is actually closest to the sun in our winter. But the sun is closer in the winter only for places in the Northern Hemisphere. This fact can be helpful in dispelling the common student/public misconception the changing Earth-sun distance causes Earth's seasons. Earth actually comes about 2 1/2 million miles closer to the sun in early January than in July. Furthermore, if our seasons were caused by changes in the Earth-sun distance, both hemispheres would experience winter and summer at the same time. (Tom McGuire) 27. Asbestos, a stringy mineral form of serpentine, has a linear crystal structure. Asbestos has recently become newsworthy as a carcinogen in building materials and fire resistant insulating materials used well into the twentieth century. Many older public buildings have required expensive repairs to take out friable asbestos that could yield
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airborne contamination. Tiny fibers of the mineral can irritate the lining of the lungs leading to a number respiratory health problems. Asbestos usually refers is usually the mineral actinolite, but can be any fibrous member of the amphibole and serpentine mineral groups. In fact, while asbestos breaks into little stringy pieces, actinolite is actually sheet silicate. The molecules bond two dimensionally as they do in the mica minerals. Asbestos is stringy because the microscopic sheets roll into tiny elongated scroll like particles. 28. The Coriolis effect can be observed in sinks and bathtubs. Over short distances, the Coriolis effect is too weak to show up, even in statistical analysis of multiple experiments. In theory, sinks in the Northern Hemisphere should drain counterclockwise a little more readily than draining clockwise. In practice, the effect is too subtle to show up experimentally on this small scale. Even tornadoes don't follow the theoretical expectation. However, in regional cyclonic development, the Coriolis effect certainly does have a major influence.(James Brandt) 29. Weather moves across the United States from west to east due to Earth's rotation. This is a half truth. If Earth were not spinning, surface winds would blow straight from the poles toward the equator. But Earth's rotation is responsible for the various wind belts, one of which is our zone of prevailing westerlies. However, Earth's rotation does not "power the winds. By the way, jet stream winds blow west to East in both hemispheres. (Nicole LaDue) 30. Felsic igneous rocks are light in color and mafic rocks are dark in color. The word "generally" inserted into the statement would make it correct. Granite and rhyolite are certainly light in color. But obsidian with an identical composition would probably be dark or even black. (Most obsidian is felsic.) The reason for this is that it only takes a small percentage of dark substances to make a solution black, and obsidian has a lot in common with liquid solutions. Smoky quartz is commonly very dark in color, but, like most obsidian samples, if it's chipped or sliced into a thin piece it becomes transparent. (Basaltic obsidian tends to be unstable, so it's rarely seen in the field.) Snowflake obsidian is a dark obsidian rock that contains partially crystallized rhyolite. But the mineral composition is uniform. Although rare, mafic rocks can also be light in color. The Cortlandt Complex , north of New York City, is an ultramafic body of deep intrusive rock that has some parts remarkably light in color. So we define felsic and mafic chemically/mineralogically. Although there is certainly a correlation with color (light or dark), it doesn't always work. (Bruce Wertovitch) 31. Shear waves (S-waves) can't penetrate Earth's core. Earth's core seems to have a solid inner core surrounded by a liquid outer core. It's not easy to investigate, but various forms of evidence do seem to support this. Although S-
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waves cannot travel through a liquid, seismologists do have evidence of S-waves traveling through the solid inner core. When P-waves (longitudinal waves) reach the inner core interface, some of the energy converts to transverse S-waves, which travel relatively slowly through the inner core. How do seismologists know? Because they detect some slow moving waves going through the inner core and they know that Pwaves can change to S-waves at a solid/liquid interface. So S-waves cannot travel through the liquid outer core, but they do appear at the edge of the edge of the inner core and they do travel through the solid inner core. (Pete Saracino) Misconceptions about the Nature of Science 1. Error in measurement needs to be eliminated. Error is implicit in any measurement. Improvements in instruments and techniques can always be used to reduce error, but error cannot be eliminated. This enlightened idea surfaces in the New York Reference Tables in the equation, "deviation (%) = difference from accepted value/accepted value x 100." The tem "accepted value" is used because we have no way to know the absolute "true value." Error can actually be very useful in scientific investigations. Variations in measured values can give important insights into the processes of measurement as well as insights into the measured value itself. Error is a necessary and often revealing part of doing science. (Susan. D. Hovorka) 2. Science can lead us to ultimate knowledge and make nature completely predictable. Science is not truth. Truth is an issue for philosophers and theologians. Science can only be our best efforts to understand nature. There seem to be clear limits to our knowledge. For example, it appears that we will never be able to predict when a particular radioactive atom will decay. However, we do know that a very, very large number of atoms do become predictable in their composite process. Planck's constant is a value well known to physicists. This constant reminds us that if the position of a very small (subatomic) particle is known very precisely, we cannot know it's velocity very precisely. If we know its velocity precisely, it's location becomes less precisely known. There is no escape. Quantum experimentation and studies of chaotic events lead to observations that humans will probably never be able to "understand" or predict. As another example, the answers to questions such as, "What was there before the Big Bang?" seem out of reach according our current grasp of physics. Even the "sacred cow" of mathematics appears to have inherent limitations as revealed by the work of the brilliant mathematician Kurt Gödel who proved in the 1930s that no system of mathematics is or can be both complete and totally consistent. (Tom McGuire) 3. The term "theory" is a clear indication of a scientific idea that less certain than a law of science. This idea breaks down pretty quickly. For example, the "Law of conservation of mass" was laid to rest when Einstein and others showed that matter can be changed into energy,
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and vice versa. Creationists like to point out that evolution is only the "theory of evolution." Both terms (theory and law) actually don't do justice to science. Nothing in science is certain. Science is not a way of proving anything. It must always be open to new discoveries and new interpretations. On the other hand, biological evolution is a cornerstone of modern biology that is accepted nearly unanimously by the scientific community based on very strong evidence that become stronger as we look more deeply. In my opinion, the distinction between the terms theory and law simply isn't meaningful in science. (Tom McGuire) 4. Atoms are like miniature solar systems. This is a very limited partial truth. We think of electrons orbiting a central mass of a nucleus like planets orbiting the great mass of the sun. But the similarities break down very quickly. For example, unlike planets all electrons are identical and they can only occur at certain very specific energy levels (orbital distances). They freely jump between higher and lower orbitals. Electrons are elusive. If you know their positions with great accuracy, you cannot know their momentums (mass & velocity) with accuracy because electrons are both particles and waves. At an elementary school level, it may be acceptable to think of atoms as little solar systems. But high school students should begin to understand the severe limitations of this model. (Eric Megli) Questionable Statements 1. Anthracite (hard coal) is the metamorphic form of soft coal. There are good arguments both for and against this statement. Soft coal does change to anthracite with deeper burial, which generally means increased pressure and temperature. But the conditions that form anthracite do not change most other sedimentary rocks into metamorphic rocks. Furthermore, anthracite has not experienced the chemical changes and crystal growth that we usually associate with metamorphic rocks. Some would argue that true metamorphism changes anthracite to graphite, although this is relatively rare. But textbooks still classify anthracite as a metamorphic form of coal. This issue really goes back to the difficulty of defining at what point a sedimentary rocks becomes a metamorphic rock. There is no definitive answer. (Jim Ebert) 2. The world faces a crisis in overpopulation and resource depletion This one is controversial. Many environmentalists favor the ideas of Stamford University author Paul Ehrlich. But Ehrlich's predictions have not faired well to date. Furthermore, the United Nations now projects that world population will level off at about 15 billion people, mainly because of changing economic realities of families. In undeveloped economies, large families insure that someone will be around to take care of their parents. So large families make sense in undeveloped nations. But as more nations become a part of the world economy, large families are a liability. Food production has increased faster than human population and shows no signs of leveling off. While we have run out of a few resources, we have generally found better
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ways to meet our resource needs. But the environmentalists are right to keep us vigilant on resource issues. We could end up trapped by our own technology. And there certainly are many localized crises that we need to address. Environmentalists' predictions of imminent worldwide crises during the past few decades have proved wrong. Clearly many of those popular pessimistic environmental pundits need to admit their errors and reevaluate their methods. But the clear trends toward increased personal health and economic security world wise cannot be guaranteed. (Tom McGuire) 3. Humans dominate Earth. In terms of biomass, insects rule. They are more hearty than humans and arguably have done more to change Earth than humans. On another level, humans can be viewed as a part of Earth. We function with other parts of the planet as another player in the whole planetary system. The key to your outlook on this issue is the point of view you choose to accept. (Tom McGuire) Science Education Issues 1. The role of the science educator is to weed out those not smart enough to be good scientists. I don't think many science educators would say this. But if you look at the critical nature of some instructors, it too often seems as if they're trying to discourage people from entering the field. Some programs, especially PhDs, make it so difficult to get the degree that the instructors are simply making education difficult for their students in the same way it was for them. Some medical schools make their programs so difficult that a person must be almost superhuman to get through. Surely that contributes to the behavior of doctors who cannot effectively relate to their patients. (Or their families) The extreme of this syndrome might be an elitist statement such as "If someone isn't a scientist, it is only because he/she isn't smart enough to be a scientist." It would certainly be a misconception to say that all scientists (or doctors) fall into this trap, but it would also be incorrect to say that this problem does not exist. Unfortunately, there's can be thin line between keeping science rigorous and discouraging people from entering science. (Tom McGuire) 2. The study of Earth science is not important for our more academic students. The root of this unfortunate opinion is probably in our educational structure and economics. Many schools have channeled their better students only into the science fields of physics, chemistry and biology. Some people point out that job opportunities are too cyclical or limited in the Earth sciences. Furthermore the Earth sciences are not on the "fast track" for college admissions. Unfortunately, we've gotten caught in a vicious spiral that feeds upon itself. A lack of our brightest students taking Earth sciences at the secondary level may have resulted in a compromise of standards in secondary Earth science. But look at the need of the public to understand natural disasters, weather and resources. Surely these are things that people need to be educated about more than the
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abstract principles of the "hard sciences." Any science field can be a rigorous. But I contend that the Earth sciences need to be addressed, especially at the secondary level, to make informed citizens of both the general population and the most academic students. (Tom McGuire) 3. Teachers can control Regents core content. The standards upon which the cores are based are actually set by the State Education Department (SED). Although committees of teachers write the core guides and exams, the content is actually determined by the State Education Department as an administrative function. A few teachers have expressed that they want to start a popular action to make changes in the statewide Regents course. But that's not the way curriculum reform in New York really works. The curricula committees get their authority and direction from SED. The current core guide was developed as an application of the 1996 MST Learning Standards. Although the committee did have some editorial options, everything had to flow from that Board of Regents approved document. The process of Regents curriculum reform is generally an effort in which teachers play a major role, but a process controlled by governmental policies and administrative decisions. (Tom McGuire)
The Meanings of Words 1. Fusion is a joining or constructive process. Sometimes. Sometimes not. The word fusion is similar to the word cleave, which we also encounter in Earth science. Both are among that small group of words in the English language that can have opposite meanings. If you cleave a mineral specimen, you're splitting it. But if you cleave to a loved one, you are binding with the person. We also use the term fusion in opposite meanings. Nuclear fusion is a process n which atoms join together to make one more massive atom. But the fusion of water is melting in which atoms move apart. It's ironic that both terms are prominent in Earth science, that each of these terms has opposite meanings, and also that their meanings are so similar.
4. Jetties are built to restore sand on beaches. This is an error in usage. Jetties are generally constructed from the shore into the water to keep channels open to boats and free of sand. They are usually built in parallel pairs. But if the structure is intended to trap sand moving in the long shore current and restore a beach, it's called a groin. In that sense, groins and jetties have opposite purposes. Jetties to prevent deposition and groins to cause deposition. A breakwater is a solid structure to prevent wave damage on the lee side. Of the three, only a breakwater may or may not connect with the shore. (Tom Bruckner) 5. Sunlight is only visible radiation. Students often find the word "light" confusing. That's because we use it in two different ways. Visible light is a part of the full electromagnetic spectrum. In this context light is
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used to refer only to the visible part of the spectrum. At other times we intend to include a broader range of wavelengths. When we talk about sunlight we often intend to include invisible forms of radiation such as infrared and ultraviolet. Perhaps we should take more care to distinguish between visible light and the broader meaning of electromagnetic or radiant energy. (Jeff Callister) 6. Frost forms by a process called sublimation. Sublimation certainly refers to the "evaporation" of ice. (That is, the change from a solid directly into a gas.) But there may be a better term for water vapor changing directly into a solid. This process is sometimes called deposition in chemistry. Deposition is probably more descriptive of the gas to solid change. One can say that frost forms by deposition and it can disappear as it sublimates. Using the term depositions for this change in state has two advantages. It helps to distinguish the gas to solid change from the solid to gas change, and it also brings us in line with the chemists. (Tom McGuire) 7. There are three states of matter. There are two problems here. First, plasma is sometimes considered a fourth state of matter. So three states probably aren't enough. A gas changes to plasma at extreme temperatures such as in stars, including the sun. In plasma electrons are no longer associated with energy levels of a particular nucleus. In fact, most of the mass of the universe is probably plasma in stars. Plasma probably isn't solid, liquid or gas. It is not clear if objects such as neutron stars and black holes can be assigned to a state of matter. Furthermore, the term "state of matter" is a widely used convention that is not well defined. For example, is glass a solid or a liquid? Like other sol ids, glass is brittle. But like liquids, glass may have no crystalline arrangement of atoms. Furthermore, even though convection is considered a property of fluids, which we usually think of as liquids and gases, the solid mantle is known to support convection currents. If you could examine at rock deep within the mantle, most of it would seem solid and old make a high pitched "clink" when struck with a hammer. So the mantle shows distinct properties of both solids and fluids. Chemists like to use the term "phases of matter" in which the atoms gain potential energy as the substance changes to a higher energy form. Under this scheme, there can be many more phases than the traditional three states of matter. So "phase" is a classification more clearly defined in chemistry than "state" of matter. (Tom McGuire) 8. We live on Earth's surface. When we talk about Earth's surface we usually mean the interface between the solid or liquid Earth and the atmosphere. But when we consider the surfaces of stars or the largest planets we usually consider the surface to be the visible top of the atmosphere. Perhaps we should call this terrestrial interface where we live by a different name such as Earth's visible surface. After all, the atmosphere is an important part of our planet. But that definition may not work when we consider planets like Venus that have a relatively
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opaque atmosphere. The diameter of Venus is generally listed as the diameter of the solid shell. This seems to be a clear conflict that has no logical resolution. (Jeff Callister) 9. Only Earth has a moon. Some students think that the term moon refers only to Earth's moon. They may fail to realize that the term moon can refer to any natural satellite (of at least a yet undefined size and not part of a ring system) of any planet. We could say many students do not understand that "a moon" does not mean the same as "the moon." If we change to the convention of capitalizing the word when to refer to Earth's "Moon," that practice may help with the distinction. (Jeff Callister) 10. Mica is a mineral, and so is feldspar. Both of these are actually families or groups of minerals and not (single) minerals. Similarly, amphibole and pyroxene are mineral group names. In those two groups, hornblende and augite are the most common mineral members. Members of the feldspar group, the most common minerals in Earth's crust, can be difficult to distinguish as minerals or mineral families. Orthoclase is pure or nearly pure potassium feldspar. This is a fairly uniform mineral in terms of its chemical composition Potassium feldspar can usually be identified in careful field observations. The other feldspars are often called plagioclase, or sodium-calcium feldspar. Plagioclase feldspar is also a mineral series. Although it's usually a mix of sodium and calcium feldspar, it's very difficult to estimate the portions of these two ions in the field. Plagioclase feldspars include albite, oligoclase, andesine, laboradorite, bytownite, and anorthite in order of increasing calcium content. So the question for us is, "How far should we break down the feldspars for our students?" In secondary Earth science, we usually call feldspar a family that includes two common varieties that we can usually tell apart. But we generally treat plagioclase as a single mineral because of the difficulty of further division. Olivine is a similar group of minerals that range from pure (or nearly pure) magnesium silicate (fayalite) to pure (or nearly pure) iron silicate (fosterite). There is a series of names for species with intermediate compositions. But those specific mineral names are seldom used. So in the Earth Science Reference Tables, and even in many college texts, the name olivine is used as if it were a single mineral. It is technically wrong to use olivine as a mineral name, but it is common usage. (Jeff Callister) 12. Stream velocity is how fast a stream flows. Technically, velocity and speed are not the same. When Earth scientists talk about stream velocity, we usually mean stream speed because the direction isn't important and it's seldom specified. It might be better to use the two terms in recognition that they are not the same. Speed is only a scalar quantity, while velocity is a vector quantity that includes both speed and direction. The current New York core document as well as the Reference
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Tables make this error in several places where they refer to stream velocity, wind velocity and velocity of seismic waves. In each case, velocity is used where the word speed probably should be. But, curiously, both document also sometimes use the correct terms in referring to speed of revolution and wind speed. So these documents contain apparent errors as well as inconsistencies with speed and velocity. This confusion is probably reflective of the way most geoscientists use the two terms. Mass and weight are also a scalar-vector pair, although scientists are usually more careful in the distinction of this pair. (Weight as a force always has a direction.) So mass and weight should not be used interchangeably. (Tom McGuire) 13. Mountains are worn away by erosion. Some authors use the word erosion to include both weathering (the physical and chemical break-down of rocks) as well as erosion (the transportation of Earth materials). The better word for this combined process is denudation. It may be preferable to restrict the word erosion to the transportation of weathered materials and use "denudation" for the combined process. Editorial Errors or Conventions The following are not really misinformation, but they point out issues that are more editorial or deal with use of language 1. Earth's surface is composed of crustal plates The plates extend to the bottom of the lithosphere, of which the crust is only a part. The terms plates, tectonic plates or lithospheric plates are all correct usage. It has also been suggested that we use the term "geosphere" for the whole Earth below the atmosphere and oceans. (Solid Earth doesn't work because of the liquid outer core.) The term lithosphere is sometimes used in this context, but lithosphere really means just the outer part of this region above the asthenosphere. Earth could (and probably should) include the oceans and atmosphere. It looks as if we do need a term for the "geosphere."(Jeff Callister) 2. Our planet is the earth. Many published sources (including Regents exams) leave out "the" and capitalize "Earth." For example, "Earth is one of the four terrestrial planets." Earth is capitalized, as are the names of Mercury, Venus, etc. "The earth" is used to refer to the material transported by earthmoving equipment. So it's still used with a small case "e" to refer to sediment, dirt or rock. This is a convention that is emerging, but certainly not used by all publishers. Is our subject area earth science of Earth science? We do live on Earth. But we don't usually capitalize biology, chemistry and physics. This issue seems to be fluid. Most publishers do not seem to capitalize, or omit "the," when referring to "the sun" or "the moon." (Earth revolves around the sun.) But Eric Megli contributes, "In an editor's
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note in book Spacetime Physics, by Taylor and Wheeler, it is written that the use of Earth, Moon, and Sun (not "the sun") is the recommendation of the International Astronomical Union. It's hard to know how much of this will ultimately prevail. I capitalize the term Regents because it refers to a specialized group of individuals or esteemed branch of the government. But my publisher prints it, "regents exam." (Tom McGuire) 3. Other solar systems are now known in space. I'd prefer to call them "planetary systems" as the term "solar" is generally a reference to a particular star; the sun. The sun is a specific object of the generic class star. I've also heard people ask if there are other "Earths" in space rather than asking about other Earthlike planets. Moon, on the other hand, has no separate generic term. One might separate specific from generic by no capitalization of moon for the generic ("There are many moons of Jupiter.") and capitalizing and/or using "the" with the specific ("The Moon is Earth's only natural satellite," or "Earth has just one moon, the Moon.") However, in the case of "solar system" it appears that we can use "planetary system" for the generic. Some people ask if there may be other "suns" out there. But it might be better to ask if there are other sun-like stars. So the clearest way to distinguish between generic (such as planetary system, star or planet) and specific (such as solar system, sun and Earth) is to use separate terms when possible. Capitalizing the specific also helps in this distinction and using "the" when the generic/specific pair has no separate terms as in the case of moon/(the) Moon also helps. But don't expect any quick and universal resolution of this issue. (Tom McGuire) Other Sources Aron, R, et. al, The Persistence of Selected Geographic Misperceptions: a Survey of Junior High through Undergraduate College Students. Journal of Geography Vol. 93 1993. pp. 247-253. (Mark Francek) Committee for Scientific Investigation of Claims of the Paranormal, CSICOP On-line: Scientifically Investigating Paranormal and Fringe Science Claims. http://www.csicop.org (Tom McGuire) Driver, Rosalind, et. al. Making Sense of Secondary Science; Research into Children's Ideas. Routledge, 1994 (Ed Denecke) Fraser, Alister B, Bad Science web pages. http://www.ems.psu.edu/~fraser/BadScience.html (Tom McGuire) National Conference on the Teaching of Evolution, Misconceptions website. http://www.ucmp.berkeley.edu/ncte/twb/misconceptions.html#monkeys (Mark Francek)
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Plait, Phil, Bad Astronomy web pages http://www.badastronomy.com/bad/misc/index.html (Tom McGuire)
NOTES: ******************************** Why do students and teachers continue to state that "HOT AIR RISES". Convection occurs because denser (colder) air falls under less dense (warmer) forcing the 'warmer' air up Warm air and helium ballons do no violate the law of gravity. They do not rise by themselves. They are pushed up. Joel Gumbiner retired-mentor ****************************************************** Other Misused terms. The Precambrian is not an era, it's now considered an eon. The general name for an instrument used to determine latitude is not a sextant but an astrolabe. A sextant is a type of astrolabe.
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There has been a great deal of research into student misconceptions in the field of Earth science. But misinformation and surprising differences of opinion also exist in books and even among relatively well-educated geoscience instructors. Many misconceptions are based on valid observations or application of correct principles, but without enough depth of knowledge to understand the limitations of these principles. Some prime examples are given in this paper. Some of these misconceptions have resulted in errors or incorrect innuendoes in New York State Regents exam items either because of errors in the state core (syllabus) or the incomplete background of teachers on the test committees. It is unfortunate that students could be penalized because their knowledge is more current or more complete than the professionals who write and review test items. This is not an article about student misconceptions or teaching methods to dispel them. Many people have done research in that field and there are many articles and books about this important issue in science education. I am looking specifically at teacher misinformation in the mainstream of our field. It is my interest to identify the specifics of this problem. I leave it to others to explore ways to correct the problem. Nor am I trying to nit pick. While many of these issues go well beyond the level of understanding that we would expect students to learn, these matters can lead teachers to convey information that is known to be incorrect. But it's important to keep in mind that even knowing the same "facts" (as we best understand them) different people will still make different rational decisions. Some of these issues are not as "black and white" as some people would have us believe. For example, an atom has some features in common with the solar system. The "solar system" model of the atom has severe limitations, but this model may be useful to a very young student who would certainly not be expected to fathom quantum energy levels. (It's not clear how well our best scientists understand quantum issues, or, if quantum is, in fact, "understandable" on a human level.) So both scientists and educators use conceptual models that are clearly limited. Furthermore, it seems to me that educators are justified in being a little more lose than scientists. I see four levels of dealing with these issues. 1) Understanding that there is controversy. 2) Understanding the nature of the controversy. 3) Consistency. 4) Collaborative or scientific resolution. My goal in this paper is bring the reader to the second level with regard to these specific issues. I've tried to be fair and accurate, but I would appreciate hearing from anyone who differs with my statements or who can lend further insights.
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I thank those who have contributed to this listing. Many ideas came from discussions on the New York State secondary Earth science listserv based at SUNY Oneonta. <http://external.oneonta.edu/mentor> I've tried to credit those who initiated discussion about a particular misconception. But the selection of misconceptions and any errors are my own. Thomas McGuire [email protected] (Mr. McGuire (BA, MAT) is a retired science chairperson at Briarcliff High School in suburban New York and the author of several Earth science books with Amsco School Publications of New York. He now resides in Cave Creek, Arizona) ***************************************************************** Geoscience Content Misconceptions 1. Convection drives tectonic plate motions. Measurements show that the speed of a plate is generally a function of the age of the subducting lithosphere at the trench. As subduction zones got older, subduction motion generally speeds up. If motion were driven by mantle convection we would expect plate speeds to be more constant. So it looks like plates are pulled progressively faster by the force of the descending slab. It now appears plates drive the horizontal components of convection more than convection drives the plates. (Tom McGuire) ********************* 1.Isostacy is the key to the subduction. 2. Flexural bending (rigid behavior of the lithosphere), as well as the gravitation force, are components of a subduction boundary. Sometimes flexural bulges (normal faults) occur ahead of the trench 3. Partial melting of the mantle (not the slab) occurs due to dewatering of the slab. The solidus of peridotite is thus lowered. I have yet to see this correctly represented in a textbook. Chris Imperial Lansingburgh High School [email protected] 2. Winds drive ocean surface currents. In fact, major ocean currents are driven by internal convection caused by differences in salinity and temperature. Flow directions are strongly influenced by the Coriolis effect.
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They just happen to line up with the prevailing winds in many locations. (Mike McDonnell) 3. Streams generally flow slower as they flow down hill. Streams usually have a concave profile, becoming less steep as they flow down hill. But the increase in water volume usually dominates over the decrease in slope. So large rivers tend to have a smooth, laminar flow that is actually generally faster than smaller streams. (Tom McGuire) 4. Seismic waves speed up with depth due to an increase in rock density with depth. Seismic wave speeds increase with increasing rigidity. The increased density factor would actually cause seismic waves to slow down. The energy waves generally travel faster with depth due to an even faster increase in rigidity/elasticity of rocks with depth. The term "plastic mantle" may be misleading us to think that rock gets more "mushy" as we look deeper into Earth. In fact, the hot rock within Earth is generally very rigid. (There is, however, a "low velocity" zone in the upper mantle (asthenosphere): where velocities of both P and S waves slow down.) (Marion Weaver & Tom McGuire) 5. Large crystals in igneous rock are primarily a result of slow cooling. If you look at pegmatites and fine-grained intrusive rocks it's clear that there's more going on here. The water content of magma is a major contributor to crystal size. Furthermore, rapid cooling of basaltic rocks does not usually make obsidian. For example, the lava flows in Hawaii are not obsidian. (Most obsidian is actually felsic in composition in spite of its dark color.) But it's still true that rocks that cool slowly do tend to have larger crystals if (!) the composition of the magma is the same. (Tom McGuire) 6. Air holds water vapor. Air doesn't "hold" water vapor. It's not like a sponge or a bucket holding water. Gases exist in the atmosphere independently. The amount of water vapor in the atmosphere is a function of its temperature, but it would be pretty much the same whether the other gases are present or not. If Earth had no atmosphere at all (a vacuum) and a pan of water were set outside, the water could still evaporate, even though there would not be any air to "hold" it. It's usually better to say that a larger amount of water vapor can exist in the atmosphere when it's warm and stay away from the word "hold." However, students often find it easier to understand relative humidity if they think about "how much moisture the air is holding, compared with what the air can hold." It's not uncommon to use simplifications that are not technically correct. This one is especially attractive as a teaching/understanding tool. In my opinion, it's acceptable to use the "h" word, but helpful if the teacher understands the limitations of this usage. To me, this is not an issue of being right or being wrong. When to use simplifications is an important issue both in science and in science education. If we approach these issues
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with an understanding of options and limitations, and an open mind, we can then make informed decisions. (Tom McGuire) 7. Seismologists measure earthquakes with the Richter scale. The actual (original) Richter scale is no longer in use because it only applied only to California events measured with a now outmoded mechanical seismometer. Furthermore, the true Richter scale topped out at about magnitude 8. Several scales are now used that are also log scales and dove tail with the Richter scale quite well. Currently, the moment magnitude, or Kanamore scale, is popular because it's a good measure of energy release in a seismic event. But it's arrived at by methods far more involved than Richter used. But the news media still like to call the modern scales "Richter" in honor of the legendary geophysicist who devised it and to avoid confusing the public. The term "magnitude" is probably more accurate. Some teachers may think that the Richter scale has replaced the Mercalli (intensity) scale. However, the Modified Mercalli scale is widely used by seismologists to map the details of seismic shaking in localized areas where there are few seismometers and detailed mapping is impossible using instruments. For example, Mercalli mapping clearly shows the increased shaking in locations on deep sediments. (The low-density cover often accentuates the shaking.) (Tom McGuire) 8. Pressure is necessary to form sedimentary rocks. Some people probably conflate pressure and compaction. (Unfortunately, many of them also go on to expound, “If pressure is needed, then that must mean elevated heat is present as well, so sedimentary rocks form from heat and pressure.”) In a recent edition of The Science Teacher, there is an article in which the author states (Jim's paraphrasing) that sedimentary rocks form after millions of years of pressure. While this is often true, it is certainly not a necessity. Clearly evaporites such as rock salt form without pressure and many other sedimentary rocks can also form right at the surface. (Jim Ebert) 9. Due to the Coriolis effect, winds curve to the right in the Northern Hemisphere. This is a simplifications that can be confusing. Some people have difficulty with it, as the winds around a cyclone curve left. A good way to think about this is to consider that the winds start to blow from the high straight across the pressure gradient toward the center of the low. They start to curve right. But if they continued to curve right they would blow away from the low pressure region. So they must then curve left to continue to circle into the low. Although the Coriolis effect pushes them to the right, the pressure gradient is stronger so they curve left (the "wrong" way, so to speak) as they circulate counterclockwise into a low Of course it's all reversed in the Southern Hemisphere.
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A related misconception is that the Coriolis effect is the "Coriolis force." In fact, it's not a force at all. It's just inertia tending to make the winds move in a straight line as we observe them on a spinning planet. We're really doing the curved motion along with Earth as the winds "try" to go straight. (Sharon Miller) 10. Wind is the dominant agent of erosion in desert regions. When some people think of deserts they envision drifting sand dunes. But most deserts locations are rocky with scattered plant cover. The majority of erosion in desert areas is caused by strong thunderstorms that are especially common in summer monsoons, which occur, among other places, in the American southwest in midsummer. Because of incomplete vegetative cover, desert areas of the United States actually experience more water caused erosion than most places along the humid eastern seaboard. (Tom McGuire) 11. Boiling is the same as vaporization. Actually, vaporization includes both boiling and evaporation. Boiling occurs at 100°C under normal Earth atmospheric conditions. (It's very dependent on upon vapor pressure.) At the boiling temperature most of the molecules in a liquid have enough energy to escape as a gas. But even well below the boiling temperature, some molecules have enough energy to escape from the liquid. (Remember that temperature is a measure of the average kinetic energy of molecules. Some molecules have more energy than others.) Evaporation allows only the most energetic molecules to escape; thus reducing the average energy of molecules left behind in the liquid. That's why evaporations is such an effective cooling process. It's also useful to understand that even at the dewpoint (100% humidity) evaporation is still taking place. It's just in equilibrium with condensation. So there is no net evaporation at the dewpoint, even though both processes are still taking place. (Steve Kluge) 12. Heat and temperature are the same. They are related, but not the same. Heat is the total energy of molecular motion/vibration in an object. It depends upon the mass of the object. But temperature is a measure of the average energy of the motion/vibration of molecules. The temperature of matter does not depend upon the mass. A teacup of hot water may have the same temperature as a bathtub of hot water. But they're very different in how much heat energy they have. (Fred Welfare) 13. Objects at 0°Kelvin have no energy. They still have potential energy. For example, the electrons occupy measurable energy levels. The substance may still be able to enter exothermic chemical reactions such as combustion/oxidation. The object may be able to fall toward Earth to yield energy. The whole object may have kinetic energy in the form of its relative motion. We therefore need to define absolute zero as the temperature at which no kinetic heat energy can be extracted or given off, but this is not a temperature at which the molecules have no energy. (Mark Heilbrunn)
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14. A liquid molecule has less energy than a gas molecule. A single molecule can't be a liquid or a solid. It's the association of molecules that make a solid, liquid or gas. I suppose a single molecule could be considered a gas, but it's better to talk about an aggregate of molecules as a state of matter. The statement in bold text above should probably be revised to read, "Molecules in a liquid...." (Steve Kluge) 15. Substances with a high specific heat absorb or release energy quickly. This statement confuses conductivity with specific heat. "How quickly" depends heavily on conductivity. (Specific heat probably does have some influence.) But the specific heat is determined by how much energy can be released or absorbed by a given mass and a given temperature difference. Metals generally have a high conductivity, but a low specific heat. In general, specific heat determines how much energy is exchanged while conductivity determines how quickly the energy is exchanged. (Tom McGuire) 16. The greatest possible relative humidity is 100%. Air in the upper atmosphere commonly falls in temperature below the dewpoint. It there are no surfaces or condensation nuclei for molecules to condense onto, air can become supersaturated and the humidity climbs above 100%. That's the reason for of "con trails" behind jets. Water deposits or condenses from supersaturated air onto the jet exhaust particles. Then the ice crystals or droplets disperse and become invisible. They're probably not evaporating. They're just becoming too thin and spread out to remain visible to us. The term "vapor trail" is unfortunate because water vapor is invisible. A "vapor trail" is really a cloud of ice particles or water droplets formed on jet exhaust particles. (Tom McGuire) 17. A magnitude 8 earthquake releases ten times as much energy a magnitude 7 event. The Richter scale was established so that each step of magnitude is ten times the amplitude (distance) of ground shaking. But due to the increasing energy in low frequency waves, the extended length of time of shaking for larger events as well as geometric considerations, the energy release is about 32 times for each step. So a magnitude 5 earthquake actually releases about 32 as much energy as a magnitude 4 seismic event. Furthermore, that energy ratio remains the same from step to step. (Tom McGuire) 18. Life on Earth has developed in response to the physical environment. This is true, but there's another side of this. Earth's physical environment has also developed in response to life. For example, the oxygen content of Earth's atmosphere became free oxygen by life processes. If it were not for photosynthesis, Earth's atmosphere would be very different, more like the atmospheres of Venus and Mars. This is a central idea of James Lovelock's Gaia theory. The physical environment affects the evolution of life and living things also have a major effect the development of the physical environment. Lovelock even carries Gaia to the point of considering our planet a
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giant living organism. He considers the atmosphere, oceans and geosphere as organs of this organism. But for most scientists, that's carrying a creative idea too far. Most think it better to limit the Gaia idea to the coupling of evolution of the organic and physical parts of the planet. (Tom McGuire & Jim Ebert) 19. The origin of the oceans is primarily from gases trapped in Earth's original core and expelled by volcanoes. The primary source of water to form Earth's oceans is not settled, in spite of a statement in the NYS Core Guide (1.2g) that mentions only outgassing. Precipitation from Earth's early atmosphere as well as water from collisions of comets have also been suggested as the primary source of the water. In spite of considerable debate and research, at this point there is no consensus about how scientists can select one theory over another. (Tom McGuire) 20. The largest earthquakes occur only near plate boundaries. While there are more seismic events where tectonic plates meet, earthquakes within the interiors of plates can be very large. The size (energy release) of an earthquake depends upon the ability of the rocks to hold stress (force) and strain (bending) before they break. The New Madrid, Missouri events of 1811-1812 were among the largest earthquakes ever known in the United States. The rocks are not as fractured within the plates as they are at the plate boundaries. So intra-plate events, although less common, might actually become larger than plate boundary events. Furthermore, they generally transmit their energy farther (larger felt/damage area) than plate boundary events. (Tom McGuire) 21. The length of the day is exactly 12 hours on the equinox. This isn't quite true in spite of what we have learned or what we teach about the equinoxes. There are a number of reasons. (1) The sun has a visible diameter, so we can see its upper portions both before its center reaches the eastern horizon and after the center point dips below the western horizon. (This effect is lengthened for observers at higher latitudes north and south where the sun has a slanted path thorough the sky and the sun takes longer to drop completely below the horizon.) (2) Earth's atmosphere refracts rays of sunlight. We actually see the sun in the morning before we cold see it if Earth had no atmosphere, and we also see it longer in the evening because of this bending of light rays. (3) The daylight period is not symmetrical around local solar noon (sun transit) so the day is not lengthened by equal amounts in the morning and evening. (4) In addition, changing atmospheric properties cause the amount of refraction to change from day to day. In spite of its name equinox, this time of the year is not defined as a time of equal day and night. Rather, it's more precise to say that the seasons change at the time the sun is exactly above Earth's equator. This can occur at any time of day. Therefore, (5) the length of daylight on the spring and fall equinoxes is unlikely to be exactly the same. If the sun crosses the projection of the equator in the sky closer to our local noon on both days, the day length is more like to be the same at the spring and fall equinoxes. This time of the transit of the equator can either lengthen or shorten the amount of daylight on the two equinoxes making the daylight periods unequal. There is a good explanation of
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these issues at two web sites, < http://www.analemma.com/Pages/framesPage.html> and http://www.bedford.k12.ny.us/flhs/science/sunrise.html. Of course, all this detail would be pretty tough to teach to young students. Perhaps it's best to just to mention #1 and to say that there are other reasons the above statement is not quite true. (Steve Kluge) A related misconception is that the sun rises perpendicular to the horizon. (Jim Lehmann) 22. The sun is overhead at noon. There are several problems here. The noon sun can not be at the zenith (straight overhead) for any observer on Earth unless the observe is located at a latitude between the tropics of Cancer and Capricorn, and the latitude where the non sun is at the zenith changes through the year. The second issue is clock noon and solar noon. Solar noon is the time the sun crosses the meridian of the sky. (The meridian is an imaginary line through the sky connecting the horizon points of due north and due south.) The precise time of solar noon changes continuously as the observer moves east or west. To keep our lives synchronized with those who live near us, we set our clocks to the same time as other clocks within our hourly time zone. Therefore the sun actually crosses the meridian as much as half an hour before or after noon. A third factor is the speed of Earth in its orbit, which causes the sun to be as little ahead or behind schedule depending on the time of year. The tilt of Earth's axis also contributes to this time difference because the sun gets a little behind schedule when its apparent motion is not parallel to Earth's equator. You can get more details if you investigate the analemma curve, which is the symbol that looks like a figure 8 printed on some globe maps. It's also known as the equation of time. See the two web sites in the item above. (Steve Kluge) 23. The major reason solar time and clock time do not progress at the same speed is the eccentricity of Earth's orbit. This error evolved from the 1970 New York Regents Earth Science syllabus. The time from solar noon to the next solar noon actually varies in an annual cycle. These factor adds up for months causing clock time and solar time to differ by as much as 15 minutes before the two gradually come back together in an annual cycle. While Earth's orbital eccentricity is the only contributing factor stated in the 1970 Regents Earth Science syllabus, the more important reason is actually Earth's tilt of 23 1/2°. The web site below shows how the two factors (elliptical orbit and tilt of axis) add up to the total discrepancy between solar time and clock time. To understand this, visit the following web site. http://www.analemma.com/Pages/framesPage.html. Then click on the tab for "summation effect." A graph there shows how the two effect are added together and their relative contributions to the total discrepancy. In addition to the text in the web site, Strahler's "The Earth Sciences" (1963) also has an excellent explanation for the time difference in chapter 3:" Time." (Steve Kluge) 24. Pluto is the outermost planet. Pluto's obit is eccentric enough that it spends pat of the time closer to the sun than Neptune. Therefore, at times, Neptune is farther from the sun and Pluto. Another problem with this statement is defining what a planet is. In general, a planet seems to be a major
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satellite of the sun or another star. But Pluto doesn't fit in. Unlike the other outer planets it's a relatively small, rocky object. Some astronomers have suggested Pluto is really a moon of another planet that got bumped or pulled out of place. A similar problem exists in defining a moon. Is there a lower limit to the size of a natural satellite of a planet that helps define a moon? The rings of the gas giants are actually composed of solid particles in orbit. Are they not considered moons because they orbit in rings or are they excluded because they are too small? As of March 2003 the identified moons of Jupiter totaled 52 and the number is still rising. I think we can identify these issues, but astronomers will need to solve them. For now, most astronomers seem to feel that Pluto is a planet, if only for reason is tradition. (Tom McGuire) 25. A radiometer spins because gas molecules bounce off the hotter black side of the vanes. Perhaps you have seen these devices that look like light bulbs with a wind vane inside. When light strikes them, the vanes turn. I've heard and seen some people state that it's the pressure of light photons that drive the motion. But the photon pressure theory would drive the motion in direction opposite to what we actually observe. The bold statement above is the explanation many of us learned from generally good scientific sources. It now appears that both are wrong. What actually happens is that at the edge of the paddles the warm gas molecules meet the cold gas molecules from the lighter side of the paddle, so molecules start creeping round the edge from the paddles from the cold to the warm area. This rapid flow of gas causes the paddles to move in the opposite direction, making it look as if there is pressure being exerted on the black side. In other words, it's the gas flowing around the edges of the vanes the drives the radiometer, not molecular collisions along the faces. (Tom McGuire)
<http://www.bbc.co.uk/science/scienceshack/backcat/adamexp/wlradiometer.shtm l>
26. The changing distance between Earth and the sun causes the seasons. This is more common as a student misconception than a misunderstanding by teachers. But there's a good way to attack this misconception. Earth is actually closest to the sun in our winter. But the sun is closer in the winter only for places in the Northern Hemisphere. This fact can be helpful in dispelling the common student/public misconception the changing Earth-sun distance causes Earth's seasons. Earth actually comes about 2 1/2 million miles closer to the sun in early January than in July. Furthermore, if our seasons were caused by changes in the Earth-sun distance, both hemispheres would experience winter and summer at the same time. (Tom McGuire) 27. Asbestos, a stringy mineral form of serpentine, has a linear crystal structure. Asbestos has recently become newsworthy as a carcinogen in building materials and fire resistant insulating materials used well into the twentieth century. Many older public buildings have required expensive repairs to take out friable asbestos that could yield
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airborne contamination. Tiny fibers of the mineral can irritate the lining of the lungs leading to a number respiratory health problems. Asbestos usually refers is usually the mineral actinolite, but can be any fibrous member of the amphibole and serpentine mineral groups. In fact, while asbestos breaks into little stringy pieces, actinolite is actually sheet silicate. The molecules bond two dimensionally as they do in the mica minerals. Asbestos is stringy because the microscopic sheets roll into tiny elongated scroll like particles. 28. The Coriolis effect can be observed in sinks and bathtubs. Over short distances, the Coriolis effect is too weak to show up, even in statistical analysis of multiple experiments. In theory, sinks in the Northern Hemisphere should drain counterclockwise a little more readily than draining clockwise. In practice, the effect is too subtle to show up experimentally on this small scale. Even tornadoes don't follow the theoretical expectation. However, in regional cyclonic development, the Coriolis effect certainly does have a major influence.(James Brandt) 29. Weather moves across the United States from west to east due to Earth's rotation. This is a half truth. If Earth were not spinning, surface winds would blow straight from the poles toward the equator. But Earth's rotation is responsible for the various wind belts, one of which is our zone of prevailing westerlies. However, Earth's rotation does not "power the winds. By the way, jet stream winds blow west to East in both hemispheres. (Nicole LaDue) 30. Felsic igneous rocks are light in color and mafic rocks are dark in color. The word "generally" inserted into the statement would make it correct. Granite and rhyolite are certainly light in color. But obsidian with an identical composition would probably be dark or even black. (Most obsidian is felsic.) The reason for this is that it only takes a small percentage of dark substances to make a solution black, and obsidian has a lot in common with liquid solutions. Smoky quartz is commonly very dark in color, but, like most obsidian samples, if it's chipped or sliced into a thin piece it becomes transparent. (Basaltic obsidian tends to be unstable, so it's rarely seen in the field.) Snowflake obsidian is a dark obsidian rock that contains partially crystallized rhyolite. But the mineral composition is uniform. Although rare, mafic rocks can also be light in color. The Cortlandt Complex , north of New York City, is an ultramafic body of deep intrusive rock that has some parts remarkably light in color. So we define felsic and mafic chemically/mineralogically. Although there is certainly a correlation with color (light or dark), it doesn't always work. (Bruce Wertovitch) 31. Shear waves (S-waves) can't penetrate Earth's core. Earth's core seems to have a solid inner core surrounded by a liquid outer core. It's not easy to investigate, but various forms of evidence do seem to support this. Although S-
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waves cannot travel through a liquid, seismologists do have evidence of S-waves traveling through the solid inner core. When P-waves (longitudinal waves) reach the inner core interface, some of the energy converts to transverse S-waves, which travel relatively slowly through the inner core. How do seismologists know? Because they detect some slow moving waves going through the inner core and they know that Pwaves can change to S-waves at a solid/liquid interface. So S-waves cannot travel through the liquid outer core, but they do appear at the edge of the edge of the inner core and they do travel through the solid inner core. (Pete Saracino) Misconceptions about the Nature of Science 1. Error in measurement needs to be eliminated. Error is implicit in any measurement. Improvements in instruments and techniques can always be used to reduce error, but error cannot be eliminated. This enlightened idea surfaces in the New York Reference Tables in the equation, "deviation (%) = difference from accepted value/accepted value x 100." The tem "accepted value" is used because we have no way to know the absolute "true value." Error can actually be very useful in scientific investigations. Variations in measured values can give important insights into the processes of measurement as well as insights into the measured value itself. Error is a necessary and often revealing part of doing science. (Susan. D. Hovorka) 2. Science can lead us to ultimate knowledge and make nature completely predictable. Science is not truth. Truth is an issue for philosophers and theologians. Science can only be our best efforts to understand nature. There seem to be clear limits to our knowledge. For example, it appears that we will never be able to predict when a particular radioactive atom will decay. However, we do know that a very, very large number of atoms do become predictable in their composite process. Planck's constant is a value well known to physicists. This constant reminds us that if the position of a very small (subatomic) particle is known very precisely, we cannot know it's velocity very precisely. If we know its velocity precisely, it's location becomes less precisely known. There is no escape. Quantum experimentation and studies of chaotic events lead to observations that humans will probably never be able to "understand" or predict. As another example, the answers to questions such as, "What was there before the Big Bang?" seem out of reach according our current grasp of physics. Even the "sacred cow" of mathematics appears to have inherent limitations as revealed by the work of the brilliant mathematician Kurt Gödel who proved in the 1930s that no system of mathematics is or can be both complete and totally consistent. (Tom McGuire) 3. The term "theory" is a clear indication of a scientific idea that less certain than a law of science. This idea breaks down pretty quickly. For example, the "Law of conservation of mass" was laid to rest when Einstein and others showed that matter can be changed into energy,
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and vice versa. Creationists like to point out that evolution is only the "theory of evolution." Both terms (theory and law) actually don't do justice to science. Nothing in science is certain. Science is not a way of proving anything. It must always be open to new discoveries and new interpretations. On the other hand, biological evolution is a cornerstone of modern biology that is accepted nearly unanimously by the scientific community based on very strong evidence that become stronger as we look more deeply. In my opinion, the distinction between the terms theory and law simply isn't meaningful in science. (Tom McGuire) 4. Atoms are like miniature solar systems. This is a very limited partial truth. We think of electrons orbiting a central mass of a nucleus like planets orbiting the great mass of the sun. But the similarities break down very quickly. For example, unlike planets all electrons are identical and they can only occur at certain very specific energy levels (orbital distances). They freely jump between higher and lower orbitals. Electrons are elusive. If you know their positions with great accuracy, you cannot know their momentums (mass & velocity) with accuracy because electrons are both particles and waves. At an elementary school level, it may be acceptable to think of atoms as little solar systems. But high school students should begin to understand the severe limitations of this model. (Eric Megli) Questionable Statements 1. Anthracite (hard coal) is the metamorphic form of soft coal. There are good arguments both for and against this statement. Soft coal does change to anthracite with deeper burial, which generally means increased pressure and temperature. But the conditions that form anthracite do not change most other sedimentary rocks into metamorphic rocks. Furthermore, anthracite has not experienced the chemical changes and crystal growth that we usually associate with metamorphic rocks. Some would argue that true metamorphism changes anthracite to graphite, although this is relatively rare. But textbooks still classify anthracite as a metamorphic form of coal. This issue really goes back to the difficulty of defining at what point a sedimentary rocks becomes a metamorphic rock. There is no definitive answer. (Jim Ebert) 2. The world faces a crisis in overpopulation and resource depletion This one is controversial. Many environmentalists favor the ideas of Stamford University author Paul Ehrlich. But Ehrlich's predictions have not faired well to date. Furthermore, the United Nations now projects that world population will level off at about 15 billion people, mainly because of changing economic realities of families. In undeveloped economies, large families insure that someone will be around to take care of their parents. So large families make sense in undeveloped nations. But as more nations become a part of the world economy, large families are a liability. Food production has increased faster than human population and shows no signs of leveling off. While we have run out of a few resources, we have generally found better
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ways to meet our resource needs. But the environmentalists are right to keep us vigilant on resource issues. We could end up trapped by our own technology. And there certainly are many localized crises that we need to address. Environmentalists' predictions of imminent worldwide crises during the past few decades have proved wrong. Clearly many of those popular pessimistic environmental pundits need to admit their errors and reevaluate their methods. But the clear trends toward increased personal health and economic security world wise cannot be guaranteed. (Tom McGuire) 3. Humans dominate Earth. In terms of biomass, insects rule. They are more hearty than humans and arguably have done more to change Earth than humans. On another level, humans can be viewed as a part of Earth. We function with other parts of the planet as another player in the whole planetary system. The key to your outlook on this issue is the point of view you choose to accept. (Tom McGuire) Science Education Issues 1. The role of the science educator is to weed out those not smart enough to be good scientists. I don't think many science educators would say this. But if you look at the critical nature of some instructors, it too often seems as if they're trying to discourage people from entering the field. Some programs, especially PhDs, make it so difficult to get the degree that the instructors are simply making education difficult for their students in the same way it was for them. Some medical schools make their programs so difficult that a person must be almost superhuman to get through. Surely that contributes to the behavior of doctors who cannot effectively relate to their patients. (Or their families) The extreme of this syndrome might be an elitist statement such as "If someone isn't a scientist, it is only because he/she isn't smart enough to be a scientist." It would certainly be a misconception to say that all scientists (or doctors) fall into this trap, but it would also be incorrect to say that this problem does not exist. Unfortunately, there's can be thin line between keeping science rigorous and discouraging people from entering science. (Tom McGuire) 2. The study of Earth science is not important for our more academic students. The root of this unfortunate opinion is probably in our educational structure and economics. Many schools have channeled their better students only into the science fields of physics, chemistry and biology. Some people point out that job opportunities are too cyclical or limited in the Earth sciences. Furthermore the Earth sciences are not on the "fast track" for college admissions. Unfortunately, we've gotten caught in a vicious spiral that feeds upon itself. A lack of our brightest students taking Earth sciences at the secondary level may have resulted in a compromise of standards in secondary Earth science. But look at the need of the public to understand natural disasters, weather and resources. Surely these are things that people need to be educated about more than the
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abstract principles of the "hard sciences." Any science field can be a rigorous. But I contend that the Earth sciences need to be addressed, especially at the secondary level, to make informed citizens of both the general population and the most academic students. (Tom McGuire) 3. Teachers can control Regents core content. The standards upon which the cores are based are actually set by the State Education Department (SED). Although committees of teachers write the core guides and exams, the content is actually determined by the State Education Department as an administrative function. A few teachers have expressed that they want to start a popular action to make changes in the statewide Regents course. But that's not the way curriculum reform in New York really works. The curricula committees get their authority and direction from SED. The current core guide was developed as an application of the 1996 MST Learning Standards. Although the committee did have some editorial options, everything had to flow from that Board of Regents approved document. The process of Regents curriculum reform is generally an effort in which teachers play a major role, but a process controlled by governmental policies and administrative decisions. (Tom McGuire)
The Meanings of Words 1. Fusion is a joining or constructive process. Sometimes. Sometimes not. The word fusion is similar to the word cleave, which we also encounter in Earth science. Both are among that small group of words in the English language that can have opposite meanings. If you cleave a mineral specimen, you're splitting it. But if you cleave to a loved one, you are binding with the person. We also use the term fusion in opposite meanings. Nuclear fusion is a process n which atoms join together to make one more massive atom. But the fusion of water is melting in which atoms move apart. It's ironic that both terms are prominent in Earth science, that each of these terms has opposite meanings, and also that their meanings are so similar.
4. Jetties are built to restore sand on beaches. This is an error in usage. Jetties are generally constructed from the shore into the water to keep channels open to boats and free of sand. They are usually built in parallel pairs. But if the structure is intended to trap sand moving in the long shore current and restore a beach, it's called a groin. In that sense, groins and jetties have opposite purposes. Jetties to prevent deposition and groins to cause deposition. A breakwater is a solid structure to prevent wave damage on the lee side. Of the three, only a breakwater may or may not connect with the shore. (Tom Bruckner) 5. Sunlight is only visible radiation. Students often find the word "light" confusing. That's because we use it in two different ways. Visible light is a part of the full electromagnetic spectrum. In this context light is
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used to refer only to the visible part of the spectrum. At other times we intend to include a broader range of wavelengths. When we talk about sunlight we often intend to include invisible forms of radiation such as infrared and ultraviolet. Perhaps we should take more care to distinguish between visible light and the broader meaning of electromagnetic or radiant energy. (Jeff Callister) 6. Frost forms by a process called sublimation. Sublimation certainly refers to the "evaporation" of ice. (That is, the change from a solid directly into a gas.) But there may be a better term for water vapor changing directly into a solid. This process is sometimes called deposition in chemistry. Deposition is probably more descriptive of the gas to solid change. One can say that frost forms by deposition and it can disappear as it sublimates. Using the term depositions for this change in state has two advantages. It helps to distinguish the gas to solid change from the solid to gas change, and it also brings us in line with the chemists. (Tom McGuire) 7. There are three states of matter. There are two problems here. First, plasma is sometimes considered a fourth state of matter. So three states probably aren't enough. A gas changes to plasma at extreme temperatures such as in stars, including the sun. In plasma electrons are no longer associated with energy levels of a particular nucleus. In fact, most of the mass of the universe is probably plasma in stars. Plasma probably isn't solid, liquid or gas. It is not clear if objects such as neutron stars and black holes can be assigned to a state of matter. Furthermore, the term "state of matter" is a widely used convention that is not well defined. For example, is glass a solid or a liquid? Like other sol ids, glass is brittle. But like liquids, glass may have no crystalline arrangement of atoms. Furthermore, even though convection is considered a property of fluids, which we usually think of as liquids and gases, the solid mantle is known to support convection currents. If you could examine at rock deep within the mantle, most of it would seem solid and old make a high pitched "clink" when struck with a hammer. So the mantle shows distinct properties of both solids and fluids. Chemists like to use the term "phases of matter" in which the atoms gain potential energy as the substance changes to a higher energy form. Under this scheme, there can be many more phases than the traditional three states of matter. So "phase" is a classification more clearly defined in chemistry than "state" of matter. (Tom McGuire) 8. We live on Earth's surface. When we talk about Earth's surface we usually mean the interface between the solid or liquid Earth and the atmosphere. But when we consider the surfaces of stars or the largest planets we usually consider the surface to be the visible top of the atmosphere. Perhaps we should call this terrestrial interface where we live by a different name such as Earth's visible surface. After all, the atmosphere is an important part of our planet. But that definition may not work when we consider planets like Venus that have a relatively
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opaque atmosphere. The diameter of Venus is generally listed as the diameter of the solid shell. This seems to be a clear conflict that has no logical resolution. (Jeff Callister) 9. Only Earth has a moon. Some students think that the term moon refers only to Earth's moon. They may fail to realize that the term moon can refer to any natural satellite (of at least a yet undefined size and not part of a ring system) of any planet. We could say many students do not understand that "a moon" does not mean the same as "the moon." If we change to the convention of capitalizing the word when to refer to Earth's "Moon," that practice may help with the distinction. (Jeff Callister) 10. Mica is a mineral, and so is feldspar. Both of these are actually families or groups of minerals and not (single) minerals. Similarly, amphibole and pyroxene are mineral group names. In those two groups, hornblende and augite are the most common mineral members. Members of the feldspar group, the most common minerals in Earth's crust, can be difficult to distinguish as minerals or mineral families. Orthoclase is pure or nearly pure potassium feldspar. This is a fairly uniform mineral in terms of its chemical composition Potassium feldspar can usually be identified in careful field observations. The other feldspars are often called plagioclase, or sodium-calcium feldspar. Plagioclase feldspar is also a mineral series. Although it's usually a mix of sodium and calcium feldspar, it's very difficult to estimate the portions of these two ions in the field. Plagioclase feldspars include albite, oligoclase, andesine, laboradorite, bytownite, and anorthite in order of increasing calcium content. So the question for us is, "How far should we break down the feldspars for our students?" In secondary Earth science, we usually call feldspar a family that includes two common varieties that we can usually tell apart. But we generally treat plagioclase as a single mineral because of the difficulty of further division. Olivine is a similar group of minerals that range from pure (or nearly pure) magnesium silicate (fayalite) to pure (or nearly pure) iron silicate (fosterite). There is a series of names for species with intermediate compositions. But those specific mineral names are seldom used. So in the Earth Science Reference Tables, and even in many college texts, the name olivine is used as if it were a single mineral. It is technically wrong to use olivine as a mineral name, but it is common usage. (Jeff Callister) 12. Stream velocity is how fast a stream flows. Technically, velocity and speed are not the same. When Earth scientists talk about stream velocity, we usually mean stream speed because the direction isn't important and it's seldom specified. It might be better to use the two terms in recognition that they are not the same. Speed is only a scalar quantity, while velocity is a vector quantity that includes both speed and direction. The current New York core document as well as the Reference
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Tables make this error in several places where they refer to stream velocity, wind velocity and velocity of seismic waves. In each case, velocity is used where the word speed probably should be. But, curiously, both document also sometimes use the correct terms in referring to speed of revolution and wind speed. So these documents contain apparent errors as well as inconsistencies with speed and velocity. This confusion is probably reflective of the way most geoscientists use the two terms. Mass and weight are also a scalar-vector pair, although scientists are usually more careful in the distinction of this pair. (Weight as a force always has a direction.) So mass and weight should not be used interchangeably. (Tom McGuire) 13. Mountains are worn away by erosion. Some authors use the word erosion to include both weathering (the physical and chemical break-down of rocks) as well as erosion (the transportation of Earth materials). The better word for this combined process is denudation. It may be preferable to restrict the word erosion to the transportation of weathered materials and use "denudation" for the combined process. Editorial Errors or Conventions The following are not really misinformation, but they point out issues that are more editorial or deal with use of language 1. Earth's surface is composed of crustal plates The plates extend to the bottom of the lithosphere, of which the crust is only a part. The terms plates, tectonic plates or lithospheric plates are all correct usage. It has also been suggested that we use the term "geosphere" for the whole Earth below the atmosphere and oceans. (Solid Earth doesn't work because of the liquid outer core.) The term lithosphere is sometimes used in this context, but lithosphere really means just the outer part of this region above the asthenosphere. Earth could (and probably should) include the oceans and atmosphere. It looks as if we do need a term for the "geosphere."(Jeff Callister) 2. Our planet is the earth. Many published sources (including Regents exams) leave out "the" and capitalize "Earth." For example, "Earth is one of the four terrestrial planets." Earth is capitalized, as are the names of Mercury, Venus, etc. "The earth" is used to refer to the material transported by earthmoving equipment. So it's still used with a small case "e" to refer to sediment, dirt or rock. This is a convention that is emerging, but certainly not used by all publishers. Is our subject area earth science of Earth science? We do live on Earth. But we don't usually capitalize biology, chemistry and physics. This issue seems to be fluid. Most publishers do not seem to capitalize, or omit "the," when referring to "the sun" or "the moon." (Earth revolves around the sun.) But Eric Megli contributes, "In an editor's
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note in book Spacetime Physics, by Taylor and Wheeler, it is written that the use of Earth, Moon, and Sun (not "the sun") is the recommendation of the International Astronomical Union. It's hard to know how much of this will ultimately prevail. I capitalize the term Regents because it refers to a specialized group of individuals or esteemed branch of the government. But my publisher prints it, "regents exam." (Tom McGuire) 3. Other solar systems are now known in space. I'd prefer to call them "planetary systems" as the term "solar" is generally a reference to a particular star; the sun. The sun is a specific object of the generic class star. I've also heard people ask if there are other "Earths" in space rather than asking about other Earthlike planets. Moon, on the other hand, has no separate generic term. One might separate specific from generic by no capitalization of moon for the generic ("There are many moons of Jupiter.") and capitalizing and/or using "the" with the specific ("The Moon is Earth's only natural satellite," or "Earth has just one moon, the Moon.") However, in the case of "solar system" it appears that we can use "planetary system" for the generic. Some people ask if there may be other "suns" out there. But it might be better to ask if there are other sun-like stars. So the clearest way to distinguish between generic (such as planetary system, star or planet) and specific (such as solar system, sun and Earth) is to use separate terms when possible. Capitalizing the specific also helps in this distinction and using "the" when the generic/specific pair has no separate terms as in the case of moon/(the) Moon also helps. But don't expect any quick and universal resolution of this issue. (Tom McGuire) Other Sources Aron, R, et. al, The Persistence of Selected Geographic Misperceptions: a Survey of Junior High through Undergraduate College Students. Journal of Geography Vol. 93 1993. pp. 247-253. (Mark Francek) Committee for Scientific Investigation of Claims of the Paranormal, CSICOP On-line: Scientifically Investigating Paranormal and Fringe Science Claims. http://www.csicop.org (Tom McGuire) Driver, Rosalind, et. al. Making Sense of Secondary Science; Research into Children's Ideas. Routledge, 1994 (Ed Denecke) Fraser, Alister B, Bad Science web pages. http://www.ems.psu.edu/~fraser/BadScience.html (Tom McGuire) National Conference on the Teaching of Evolution, Misconceptions website. http://www.ucmp.berkeley.edu/ncte/twb/misconceptions.html#monkeys (Mark Francek)
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Plait, Phil, Bad Astronomy web pages http://www.badastronomy.com/bad/misc/index.html (Tom McGuire)
NOTES: ******************************** Why do students and teachers continue to state that "HOT AIR RISES". Convection occurs because denser (colder) air falls under less dense (warmer) forcing the 'warmer' air up Warm air and helium ballons do no violate the law of gravity. They do not rise by themselves. They are pushed up. Joel Gumbiner retired-mentor ****************************************************** Other Misused terms. The Precambrian is not an era, it's now considered an eon. The general name for an instrument used to determine latitude is not a sextant but an astrolabe. A sextant is a type of astrolabe.
Teacher Misinformation
Thomas McGuire
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