Policing The Textbook Police

Steven Dutch, Natural and Applied Sciences, University of Wisconsin - Green Bay
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Or, The Gang That Couldn't Shoot Straight

I recently published an article critical of the textbook publication process, and got a complimentary letter from an outfit called Textbook Trust, who apparently thought I was on their team. The heart of their packet was a long table of "errors" in a secondary school textbook, Earth Science (Holt, Rinehart, Winston). The Textbook Trust felt strongly enough about the errors to send a letter to the administration of every single college faculty member listed as a contributor to the text.

That sort of effort goes way beyond mere dissatisfaction with a bad text and suggests a broader agenda, perhaps building up to a campaign to intimidate or harass people who might be tempted to put things in textbooks that particular pressure groups don't like. We're already all too familiar with this process in social science teaching, from both the right and the left. The agenda of this particular group isn't obvious from their Web site, but some of the things they identify as "errors" suggest hostility toward environmental issues. Some of the geological bloopers are so bad I suspect a hostility toward the conventional view of earth science in general.

Below is the table I received, with a column of additional commentary by me. A few miscellaneous remarks are in black, but most are color coded.

If the criticism of the text is correct and the error is significant, the note is in blue. Three of the 29 entries are in this category. In my experience writing encyclopedia articles and my one foray into doing a pre-college chapter, a lot of the butchery in texts is not the fault of the scientist contributors but is the work of editors looking to "simplify" the text. As a result, topics get rearranged and details omitted that look harmless to the editor, and may even make the text more "readable," but in fact often introduce serious errors. This happens, for the most part, after professionals have made their contributions, and even if they point out errors in galleys, the corrections may not be made.

If the criticism is correct but involves something unlikely to improve student understanding (in other words, pedantic) the note is in green (8/29). For example, one "error" deals with the discovery of gold in California. The text gives the date as 1848, but the table claims that there was mining as early as 1842. Does anybody really care, since the historically important event was the 1848 discovery?

If the criticism is based on faulty logic or misreading of the text itself, the note is in purple (6/29). These comments are a mixed bag, but generally the reviewers are criticizing the text for something they interpret it as saying, rather than what it actually says.

And if the criticism is flatly erroneous, the note is in red. Nine of the 29 entries are in this category, and they include some dillies. Water doesn't expand with temperature, mineral deposits don't form from hot solutions, magma isn't lighter than solid rock, carbon dioxide does not have a liquid state, and continents and tectonic plates don't collide. Total ignorance of earth science is the nicest thing you can say about this "review."

According to “Earth Science”     Conventional Knowledge (Alleged Errors) Analysis
P. 3.  “1899.  The Rosetta stone is discovered in Egypt.  It enables scholars to decipher Egyptian hieroglyphics.” 1799--when Napoleon Bonaparte’s army  occupied Egypt. The criticism is correct, but this could be a typo made after the review process: a proofreading rather than factual error.
P. 3.  “1970.  The United States holds its first Earth Day on April 22.  More than 20 million people participate in peaceful demonstrations to show their concern for the environment.” 20 million people would have been 10%  of the population of the United States. No demonstrations involving even 1%  of the population of the United States have been conducted on one day. Correct.
P. 8.  “Meteors are the flashes of light seen when objects fall from space into our atmosphere.” Meteors are the objects. Well, if you want to get this pedantic, the actual meteors are too small to be seen, and what is actually seen is incandescent atmosphere and vaporized matter from the meteor.
P. 9.  “Astronomers estimate that there are 100 billion billion stars in the sky.”, and P. 9.  “Astronomers estimate that there are more than 100 billion billion stars in the sky!” No close estimate of the number of stars  has been established.  It’s not likely to be  a round number such as 100 billion billion.  It’s many times higher. Correct, but hardly likely to improve understanding.
P. 12. “It is about 12 m long and appears to weigh about 4 tons.  It is an allosaur, the most common meat-eating predator of the time.” For a 4 ton (8,000 pound) animal to be the most common meat-eating predator, there would need to be a very high number of other types of animals  available all the time and slower- moving than this ponderous reptile. I'm curious to see what other types of predators there are. But a large predator will never be the most common predator in any ecosystem.
P. 16.  “…the eight bones found in New Mexico were indeed from a newly discovered dinosaur species that was probably 45 m long and weighed at least 100 tons.” 100 tons (200,000 pounds) which is distributed over 45 m (about 140 feet) is about 1400 pounds per foot of length. With four legs, this means that each leg would need to support 50,000 pounds in a standing position, and  66,667 pounds in a walking stance with one foot raised. If the critter had an average cross-sectional area of only one square meter, it would have a volume of 45 cubic meters and weigh about 45 metric tons. So those numbers don't look too out of line. Presumably this was a sauropod and might have spent much of its time partially buoyed by water. The load criticism is only valid if the bones are too small to support such weight. And no evidence is provided to cast doubt on the weight figures. They're simply dismissed out of hand.
P. 18. “As temperature increased, the volume of the oceans would expand, causing sea level to rise.” Water is virtually incompressible or expandable with temperature in most ranges of liquid state. Water at 100 C is actually about 4% less dense than water at 0 C (i.e. has expanded in volume by 4%). A one degree rise in temperature through the whole volume of the oceans would result in a volume increase of 0.04%, or, if we take the average depth of the oceans as 5000 m, about 2 m of sea level rise. I think it's a fairly silly part of the global warming debate, since other causes of sea level rise will be far more significant, but water does expand thermally.
P. 18.  “In states such as Florida and New York, millions of people live in cities near the coast at an elevation of 8 m above sea level. If sea level rose only 8 m, these cities would be underwater!”  The likelihood of a change in sea level of 0.08 meter (about 3 inches) is remote, let alone 8 meters (about 25 feet). The place to challenge this is where a sea level change of 8 meters is predicted. If sea level rises by 8 meters, those cities will be under water.
P. 20. “If you have been in a greenhouse, you know that it is usually warmer inside than outside.  This is because sunlight not only heats the greenhouse directly after passing through the glass, but also reflects off the Earth’s surface, producing heat that is trapped inside the greenhouse.” Sunlight that is reflected off anything, including “the Earth’s surface”, is not available to heat that thing.  Sunlight that reflects off the floor of a greenhouse generally radiates out the glass—that’s why one can see the floor through the glass from outside the greenhouse.  A greenhouse is warmer inside than outside because the warmed air is not allowed to vent outside and glass is a very good heat insulator. If the greenhouse were the same temperature as the surrounding air (like on a hot summer day) it wouldn't make any difference if it were open to the outside or not. Prevention of mixing with outside air is only an issue because air inside the greenhouse is warmer. Why is it warmer? The answer is that sunlight absorbed (not reflected) in the greenhouse warms the inside, and that sunlight is reradiated in the infrared, to which glass is opaque, so heat is trapped. It is perfectly possible to have the reverse situation, say in a metal shed, where visible light is blocked but infrared is transmitted, and then the interior of the shed can be colder than its surroundings, and prevention of mixing would act to keep the interior cooler. Prevention of mixing is only of secondary importance. Saturn's moon Titan has a "negative greenhouse effect" and is actually colder than a body with no atmosphere would be at the same distance from the sun.
P. 25.  “Normal body temperature 98.6F.” Recent studies have placed the normal temperature for measurements under the tongue at 99+F.  There is actually a range of temperatures during a 24-hour period, with no single normal body temperature. The fact that there is no single body temperature, or that temperature fluctuates over time, doesn't preclude there being an average value. How does the existence of variations affect the average value?
P. 29.  “According to Boyle’s law, for example, if you increase the pressure outside a balloon, the balloon will get smaller.  This law is expressed as the following formula:  P1 X V1  =  P2 X V2  ”   Boyle says this is only true if the temperature  remains constant. A heuristically justifiable simplification is not an error. Unless there's a specific point that needs to be made about temperature, temperature dependency can be deferred until it's needed.
P. 30.  “As you are reading this, you are moving around at 1,670 km/h.  Sound impossible?  It’s true.  That’s how fast the Earth rotates on its axis.” Rotation of the Earth on its axis is measured in degrees or radians per time, not distance per time.  The only places on the Earth that are moving at 1,670 km/h (about 1050 miles per hour) are on the equator.  Every place else is slower—all the way to zero at the poles. Correct.
P. 34.  “The Greeks thought that the sphere was the most perfect form and that the Earth therefore had to be a sphere.” These unidentified Greeks were not applying the scientific method. Both quotes are equally bad. Ptolemy stated explicitly that the earth was spherical and gave observational evidence.
P. 36.  “Self-Check.  Does the Earth rotate around the geographic poles or the magnetic poles?.”  P. 564.  “Self-Check Answers. … The Earth rotates around the geographic poles.” The geographic poles are points, not lines. The Earth rotates around its axis. (See the quote for p. 30.) Correct, but hardly likely to improve understanding.
P. 41.  “Actually, Africa is 15 times larger than Greenland.” Actually, Africa (11,700,000 sq. mi.) is 14 times the size of Greenland (840,000 sq. mi.). Correct, but hardly likely to improve understanding.
P. 43.  “Satellites can detect objects the size of a baseball stadium.” Cameras on satellites can discern objects a couple inches across. So I guess they can see a baseball stadium, too.
P. 56. “1680.  The dodo, a flightless bird, is driven into extinction by hunters.  It is the first extinction of a species in recorded history.” The first extinction of a species in recorded history? The dodo was probably the first extinction to be specifically recorded when it happened.
P. 57. “1848.  Gold is discovered in California.” In 1842 gold was discovered and mined in Placerita Canyon north of Los Angeles. Gold was later discovered in 1848 at Sutter’s Mill east of Sacramento. So I guess this means gold was discovered in California in 1848. Just not for the first time. More to the point, who cares that there was a discovery in 1842, when the historically significant event was in 1848?
>P. 58.  “Gems are valuable not because of the elements they contain but because of how their atoms are arranged.” Gems are valuable because some people are willing to pay comparatively high prices for them. And they're willing to pay because of the properties of the minerals, which are determined by their compositions and crystal structures. That's why diamonds are pricier than charcoal even though both are made of carbon.
P. 60.  “A mineral is inorganic, meaning it isn’t made of living things.” The term “inorganic” in chemistry refers to molecules that do not contain carbon, with a few exceptions.  Most living things have many minerals in them, including both organic and inorganic. Better phrasing would be minerals aren't made by living things. But how did we get from minerals not being made of living things to living things containing minerals?
P. 63. “Halides are compounds that form when atoms of the elements fluorine (F), chlorine  (Cl), iodine (I), or bromine (Br) combine with sodium (Na), potassium (K), or calcium (Ca). Halite (NaCl) is better known as rock salt.  …Halide minerals are often used to make fertilizer.” In soils halides, such as NaCl (salt), generally inhibit growth in plants. Halides are compounds of cations with halogens. Calomel (HgCl),  Cerargyrite (AgCl) and Atacamite (Cu2Cl(OH)3) are also halides. The cations have nothing to do with the definition of a halide. So the textbook watchdogs missed the major error in this selection.

While fertilizer isn't the best example of a use for halide minerals, potassium halides are used in fertilizers. Halides are most commonly used as sources of halogens, and fluorite is used in smelting

P. 66.  “The specific gravity of gold, for example, is 19.  This means that gold has a density of 19 g/cm3.  In other words, there is 19 times more matter in 1 cm3 of gold than in 1 cm3 of water.” It’s 19 times, not 19 times more. Actually it’s 19.3 times. Correct, but hardly likely to improve understanding.
P. 68.  “Almost all known minerals can be found in the Earth’s crust.” And the rest?  What are they? Meteorites, lunar rocks, high-pressure forms in the mantle.
P. 69.  “It [water] then reacts with minerals in the walls of the cracks [deep in the Earth’s crust] to form a hot liquid solution.  Dissolved metals and other elements crystallize out of the hot fluid to form new minerals.  Gold, copper, sulfur, pyrite and galena form in such hot-water environments.” Gold, copper, sulfur, pyrite and galena do not dissolve in water. They may not dissolve in tap water but they do dissolve in hot solutions of the right pH and oxidation potential. Gold, copper, sulfur, pyrite and galena do form from hydrothermal solutions exactly as the textbook describes
P. 72.  “The karat is a measure of the purity of gold. … If you have a gold nugget that is 16 karats, then 16 parts out of 24 are pure gold— the other 8 parts are composed of other elements.” The “karat” system is used only with manufactured gold items and involves placing a “K” or “Karat” mark on the item. Gold nuggets and ore don’t use the  “karat” system. Correct, but hardly important.
P. 83.  “Magma is usually less dense than the surrounding rock, so it tends to rise to higher levels of the Earth’s crust.” If magma is usually less dense than the surrounding rock in the Earth’s crust, shouldn’t the entire Earth’s crust be continually falling into the less dense  magma below? Magma is generally about 10% less dense than the equivalent solid rock. The crust is sinking into the plastic (not liquid) mantle - at least the oceanic crust is - continental crust is too light. The reason that we're not constantly sinking into magma is that, above the core, the earth is solid and magma only occupies small pockets.
P. 87.  “Composition.  Sometimes fluids like water and carbon dioxide enter a rock that is close to its melting point.  When these fluids combine with the rock, they can lower the melting point of the rock enough for it to melt and form magma.” Carbon dioxide does not have a liquid state.  The temperatures of nearly molten rock are vastly higher than liquid water, and any water that approached such rock would vaporize before reaching the rock’s surface. Carbon dioxide does not have a liquid state at 1 atmosphere but I see tank cars full of liquid CO2 all the time - that's how it's shipped commercially. Liquid carbon dioxide has been found in deep-ocean sediments. Geologists generally refer to water and CO2 as volatiles but fluids is certainly acceptable; below a few km depth the actual physical state is supercritical anyway. Yes, they do combine with rocks and reduce their melting points, especially water. Dewatering of the descending crustal slab is a significant part of the reason volcanoes occur at subduction zones.
P. 97.  “When conditions within the Earth’s crust change because of collisions between continents or the intrusion of magma, the temperature and pressure of the existing rock change.” Continents don’t collide. Even tectonic plates don’t collide.  A collision implies an appreciable relative velocity between the two colliding objects. . Continents and tectonic plates do collide. That's the accepted nomenclature in plate tectonics.
P. 490.  “Hold your compass flat in your hand. Turn the compass until the N is pointing straight in front of you.  (The needle in your compass will always point north.)  Turn your body until the needle lines up with the N on your compass. You are now facing north.” Magnetic north, not true north.  A correction for magnetic declination needs to be made at each point on the Earth’s surface for the difference between magnetic north and true north, oftentimes many degrees.  That's what it says on p. 36! Correct.

It Doesn't Stop Here

In addition to the table, Textbook Trust's Web site (and the packet they sent me) also includes two figures. One is a standard ball-and-stick model of sodium chloride. The criticism of this figure is:

Atomic structure usually depicts an atom's nucleus and electrons. The chemical bonds between the sodium and chlorine atoms in a molecule of sodium chloride exist only between one atom of each. The bonds do not extend to six of the other element's atoms.

Wow. This is a capsule description of how to fail chemistry:

The illustration is correct. The critique is completely wrong. Another illustration shows the atomic arrangement in gold, then a cube of gold, then finally a crystalline mass of gold. The criticism reads:

The atomic structure of an element usually depicts an atom's nucleus and electrons. Gold crystals don't come in exact cubes, as the photo of gold crystals shows.

Gold generally does not crystallize as cubes, but has been known to on occasion. A better example would have been copper, which has the same atomic structure but where cubic crystals are much more common. There is nothing whatsoever wrong with the illustration.

Oh, California

I was also blessed with an excerpt from a geography text, Oh, California, in which a table lists four major provinces of California and a list of important places in each. Mono Lake is listed as one of the natural features of the desert, with the indignant remark "Mono Lake is actually in Sierra Nevadas."

Mono Lake is not in the Sierra Nevada (there's only one of them). The Sierra Nevada mountain front forms the west shore of Mono Lake, but Mono Lake is part of the high desert, not the Sierra Nevada.

If this is the caliber of public interest groups influencing textbook decisions, we are in serious trouble.

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Created 27 February, 2006;  Last Update 30 August, 2011

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