The teacher resource binder accompanying the kit makes a number of factual errors. This listing of errors includes only those pertaining to environmental concepts.

Specific items:

• Overview, p. 5: "heat sink...reradiating infrared"

  Avoid the term "reradiate" if possible. "Reradiate implies the original radiation was stored and then released, which is not the case. "Radiate" is better.

• Overview, p. 6: "greenhouse effect...Some experts suggest that we are on the verge of global catastrophe, while others deny the effect exists"

  No experts deny the greenhouse effect; most deny the catastrophic predictions associated with the global warming hypothesis. This statement confuses the greenhouse effect with global warming. (Also, this statement in conjunction with one 3 lines later, "The greenhouse effect is a well-established phenomenon" leads students to incorrect conclusions regarding the nature of knowledge and consensus in science.)

• Overview, p. 6: "Life in the Greenhouse" (particularly "As infrared heads for space, it reflects back to Earth from the atmospheric shield.")

  Explanation of the greenhouse effect is wrong. Water vapor is the most important greenhouse gas. Infrared is absorbed by greenhouse gases, not reflected. Heat does not build up, but the Earth's radiation balance is modified. The phenomena is not important in heating greenhouses, parked cars, and solar houses; these are primarily heated by lack of convention with surrounding air. (Statement "Still, there is good reason to modify..." is contradicted by the preceding statement.)

• Overview, p. 7: "Our students must know that the Sun is the source of energy that will power our modern world."

  In this context, the statement is opinion, not fact.

• Investigation 2, p. 4: "Some of the energy that is absorbed by Earth is reradiated from the surface as infrared radiation (heat energy). The water vapor and gases in Earth's atmosphere trap some of the reradiated heat and thus help to maintain a fairly uniform global temperature."

  Explanation of greenhouse effect is wrong. The text confuses thermal energy (heat) and infrared radiation. All energy absorbed by the Earth heats the Earth, which in turn must radiate infrared radiation at an equal rate. "Reradiated" is a confusing term. Heat is not trapped by greenhouse gases.

• Investigation 2, p. 27: "...Venus has a very thick atmosphere that absorbs most of the Sun's energy it receives. Venus's atmosphere acts as a very efficient greenhouse."

  Understanding of the greenhouse effect is incorrect. Clouds in Venus's atmosphere reflect most of the sunlight it receives (about 70%). The thick carbon dioxide atmosphere gives a significant greenhouse effect, but (as discussed above) this is not the same effect as in a greenhouse.

• Investigation 3, p. 4: "most sections of the U.S. receive ample solar energy all winter long to heat water and warm a house."

  This statement is ambiguous enough to have a correct interpretation, but the obvious interpretations are wrong. When reduced isolation due to low Sun altitude, shorten daylight hours, and cloud cover are considered, houses in the northern U.S. cannot be adequately heated by solar energy in winter.

• Investigation 3, p. 5: "Because the clear cover is only slightly transparent to the infrared radiation, heat stops inside the covered solar water heater... This is essentially the greenhouse effect..." (following paragraph)

  Greenhouse effect is misunderstood. The solar water heater and cars described heat up primarily due to lack of convection of air inside the glass or transparent cover with surrounding air.

• Investigation 3, p. 6: "greenhouse effect..."

  Explanation of the greenhouse effect is wrong.

• Investigation 3, p. 6: "Earth's atmosphere is composed primarily of nitrogen and oxygen with small percentages of carbon dioxide, methane, water vapor, chlorofluorocarbons (CFCs), and oxides of nitrogen."

  Correct listing of constituents by decreasing abundance would be nitrogen, oxygen, argon, water vapor, carbon dioxide, neon, helium, methane, krypton, ozone, helium, nitrous oxide, and others. Many other naturally occurring gases are orders of magnitude more abundant than CFCs.

• Investigation 4, p. 4: "The fact is, we are burning up the world's supply of these so-called fossil fuels. And when these fuels are gone, it could be pretty cold in a lot of homes around the world."

  Statement is misleading regarding issue of resource depletion. The two statements will tend to lead students to erroneously conclude that these fuels will be depleted in the near term and/or that the depletion will occur abruptly. Rates of increase for fossil fuel consumption have decreased primarily because the rate of increase in demand has slowed, not because of resource depletion.

• Investigation 4, p. 7: "Life itself is a gift from the Sun"

  Imprecise statement.

• Investigation 4, p. 12: "Explain that many of the fuels we use to generate energy to heat our homes are nonrenewable fossil fuels, such as gas, coal and oil...Suggest that there is an alternative...solar energy."

  Omits reference to nuclear power and hydroelectric power, which provide 20% and 8% of U.S. electricity, respectively.

• Investigation 4, p. 17: "Introduce Greenhouse Effect... This process is called the greenhouse effect."

  The process that heats a greenhouse or car is correctly described, but it is not correctly called the greenhouse effect. The diagram on this page is misleading, since it implies that infrared light rather than heated air is trapped by the greenhouse.

• Investigation 4, p. 18: "Introduce Global Warming..."

  Explanation of greehouse is incorrect. Heat (thermal energy) is confused with infrared radiation. Statement "heat builds up" is misleading, as is diagram.

• Science Stories (teacher's guide), p. 13: "What are the advantages and disadvantages of solar ovens?"

  Additional disadvantages: they can only be used when sunshine is available, they are more limited in where you put them, they require more knowledge to make and use.

• Science Stories (teacher's guide), p. 14: "What are the advantages? [It does not pollute the environment; it does not use up the earth's resources.]"

  Manufacture of solar cells requires mineral and metal resources. The manufacturing process produces toxic wastes as a byproduct.

• Science Stories, p. 2: "Energy from the Sun reaches us as heat and light"
  p. 12: "The Sun is a source of light and heat."
  p. 16: "The Sun gives us light and heat. These two things are separate forms of energy. Light is visible. We can see it. Heat is invisible. We can't see it, although we can see its source, such as the Sun or a fire."

  Need to clarify difference between thermal energy and infrared light/radiation, both of which FOSS calls "heat." It is better to call infrared light "infrared light" (and not call it "heat"), so students don't confuse the two and so students can grasp that infrared light is a means of transferring heat.

• Science Stories, p. 3: "Spaceships such as the space shuttle...contain solar panels that collect the Sun's heat and light."

  The space shuttle is not equipped with solar panels (it occasionally carries experiments that may have solar panels). The shuttle power in orbit is primarily from batteries.

• Science Stories, p. 24: "The biggest challenge facing the use of solar cells is to bring down their cost. If this happens, many experts believe that photovoltaics could provide most of our energy needs by the end of the next century."

  For practical reasons, it is impossible for conventional photovoltaics to ever meet most of our energy needs. The cost can only be brought down so far, because it takes a solar cell years to collect energy equal to what went into the manufacture of the cell. Several problems besides cost are not addressed. While there is no problem in principle with photovoltaics being a significant supplement to electrical power usage, most energy use in the U.S. is for transportation and industry, where solar cells are not a realistic solution.

• Science Stories, p. 26: "But what about third-world countries... In such countries, more than 2 billion people burn wood for cooking. There is an answer to this problem. People can use solar cookers."

  "2 billion" may overstate the rural population of regions with reliably available sunlight, which is the target population for solar cookers.

© 2002 by Wm. Robert Johnston.
Last modified 13 May 2002.
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