Gr 2-4-The first book begins with a superficial explanation of simple machines and their uses and then describes the mechanical advantage provided by inclined planes. Oversimplification throughout creates confusion, as when the text reads, "An inclined plane is a fancy term for a simple machine." Although the work formula is included, the wording is not clear enough to make the comparative point about the inverse relationship between distance and force in doing work. Some of the statements are misleading: "Inclined planes work because of gravity." This may be true for an object moving down the incline, but not one being moved upward. Sally M. Walker and Roseann Feldmann's Inclined Planes and Wedges (Lerner, 2001) is a better example of clear, well-organized science writing. The second book begins with examples of simple machines, then discusses the advantage of wheels. Unfortunately, the writing is so oversimplified that it is counterproductive. "Friction is a force that happens when two objects are rubbed together. Friction can slow movement." Forces don't "happen," and friction always slows movement. Walker and Feldmann's Wheels and Axles (Lerner, 2001) not only gives better explanations of physical principles, but also shows the use of these principles in everyday machines. In both books, the experiments are easy to do and are representational of the concepts, but they aren't complete in their explanations. The full-page, color photos are clear, and those illustrating the experiments are helpful.-Lynda Ritterman, Atco Elementary School, Waterford, NJ Copyright 2003 Reed Business Information.
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A Wedge
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Product Details
| BN ID: | 2940170797813 |
|---|---|
| Publisher: | Rourke Publishing, LLC |
| Publication date: | 01/01/2004 |
| Series: | Physical Science - How Can I Experiment With Simple Machines? |
| Edition description: | Unabridged |
| Age Range: | 8 - 11 Years |
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