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from The Textbook Letter, November-December 1992

Reviewing a middle-school book in the Prentice Hall Science series

Motion, Forces, and Energy
1993. 144 pages. ISBN of the teacher's edition: 0-13-986670-1.

What a Display of Ignorance!

Lawrence S. Lerner

Motion, Forces, and Energy is worthless, but it is also remarkable. I'm amazed that the writers have been able to pack so much bad "science" -- so much misinformation, error and ignorance -- into a mere 144 pages. The book is remarkably bad in other ways as well, for it displays false "history," bad writing, defective pedagogy, and a patronizing attitude toward blacks.

Bad "Science"

The material in Prentice Hall's book attains a spectacular level of wrongness. For example:

Nor do the writers have much sense of real-world quantities. On page 17, they guess that a cheetah can run at 2 kilometers a minute for 4 minutes! (Cheetahs may attain such a speed, but only for a matter of seconds.) On page 19 they ask the student to imagine that he is rowing a boat at 16 kilometers an hour! On page 33 there is an exercise involving freight cars that travel directly toward each other, one moving at 14 meters a second, the other at 10 meters a second, until they collide. The writers ask: "If the two cars collide and stick together, what will be the direction of their resulting motion?" Answer: If two freight cars collide when their relative speed is 24 meters a second, or about 50 miles an hour, they will end up as scattered debris.

False "History"

The book has a lot of pseudohistorical items that show how little the writers know about the history of science. For instance:

Bad Writing

Here's some of the stuff that tries to pass for writing in Motion, Forces, and Energy. On page 23: "When a roller coaster climbs a hill, it decelerates because it is slowing down." Page 27: "Why must the engines of supertankers be shut off several kilometers before they need to stop?" Page 30: "The time between each flash is 0.1 second." Page 38, in a note to the teacher: "Awesome in size and grandeur, the Mayas completely rebuilt their temples every 52 years . . . ." (Of course, that was no trick at all for people who were so awesome!) On page 60: "What do you predict is happening in the picture?"

Defective Pedagogy

The pedagogy is no better than the content. The book is incoherent and fails to furnish students with a "road map" that might guide them through the material. Quantitative exercises are far too few, so students will not be able to follow the book's treatment (such as it is) of mechanics, and the writers see mathematical formulas as mere rules that can be used without thought. The formulas are often wrong, too!

The teacher's edition offers a load of notes that are ridiculous. I've already cited some of these. Here are a few more:

Patronizing of Blacks

The Prentice Hall writers pander to blacks, patronizing them in the process.

On page 86, in the chapter about work and power, a "Multicultural Opportunity" note to the teacher says: "During the 1960s, power referred to a political movement, often designed to gain rights for minority groups." This looks like a garbled effort to invoke the Black Power movement, though the writers seem afraid to say its name. Do they really think that the word power had no political meaning, or that the phrase political power didn't exist, until the 1960s? The writers have made a futile effort to invent a connection where none exists.

Perhaps the worst instance of pandering comes on page 89, where the teacher encounters a "Multicultural Opportunity" note about a black man named McCoy. The story is presented as if it were true, but it is obviously false and comes from an absurd source. [See "The Fake McCoy" in this issue of The Textbook Letter.]

On page 47 we see that blacks aren't the only beneficiaries of the writers' condescension. As if to show how little they know or care about people other than themselves, the writers make a miserably poor effort to concoct a "Multicultural Opportunity" note about gravity! The teacher reads that in some other parts of the world, the value of g (the acceleration due to gravity) differs slightly from the value measured at Washington, D.C. Imagine that! What the teacher does not learn is what this has to do with anybody's culture. Maybe the lesson is that foreigners have to be rather clever, in their own cute ways, to survive in places where a dropped object may take an extra millisecond to reach the ground. In any event, the writers wrongly call g a "force" -- and by giving a wrong value for g at the North Pole, they destroy their own account of how g varies around the globe.

As I inspected Motion, Forces, and Energy, I typed nine pages of notes about its faults and failures, and especially about the writers' ignorance of science. In the space available for this review, I have been able to give only a fraction of my observations, but I think I have said enough to make my point: Prentice Hall's book is not fit for human consumption.


Lawrence S. Lerner is a professor in the Department of Physics and Astronomy at California State University, Long Beach. His specialties are condensed-matter physics, the history of science, and science education.

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