Project 2061 Middle and High School Science Textbooks A Standards-Based Evaluation

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Does the material include accurate and comprehensible representations of the key ideas?

Explanation. This criterion highlights the importance of using a variety of representations to make abstract ideas intelligible to all students. Different representations highlight different aspects of an idea and provide a variety of opportunities for the idea to connect to other students' ideas and become embedded in a student's knowledge system. Possible modes of representation include drawings, diagrams, graphs, images, analogies and metaphors, models and simulations, and role-playing. Representations need to be clear so that students can understand fairly quickly which ideas are being represented and how. In addition, because representations typically highlight only some aspects of an idea, care must be taken that they represent the real thing as accurately as possible (or that they involve students in considering which aspects of the real thing are represented by the model and which are not).

The number of representations that would be considered "sufficient" will depend on the complexity and level of abstractness of the idea being presented. For example, the idea that "About two thirds of the weight of cells is accounted for by water. . . ." (Benchmark 5C6–8#4) probably requires fewer representations (if any) than the complex and highly abstract idea that "Atoms and molecules are perpetually in motion. Increased temperature means greater average energy of motion, so most substances expand when heated. . . ." (Benchmark 4D6–8#3).

Indicators of meeting the criterion

1. Representation is accurate (or, if not accurate, then students are asked to critique the representation).
2. Representation is likely to be comprehensible to students.
3. Representation is explicitly linked to the real thing.

Rating Scheme
Excellent: The material includes a sufficient number and variety of representations that meet indicators 1–3 and none of the representations included in the material are inaccurate. (In order to judge whether there is a sufficient number and variety of representations, reviewers should first consider which key ideas require representations and then decide whether these are adequately represented. However, reviewers are not expected to evaluate and rate each idea separately and average the scores.)
Satisfactory: The material includes some representations that meet indicators 1–3 and few (if any) of the representations included in the material are inaccurate. (In some cases, including one accurate and comprehensible representation for a specific idea may be sufficient for a material to receive a "satisfactory" rating. However, most of the key ideas must be adequately represented.)
Poor: Even though the material includes a few representations that meet indicators 1–3, few or none of the key ideas are adequately represented.

Examples

To see the text of an indicator, place your mouse cursor over the relevant indicator number. The explanation will appear on your screen.

 Key to Chart Symbols Example(s) meet(s) the indicator. Example(s) do(es) not meet the indicator. Example(s) partially meet(s) the indicator. Not used to illustrate the indicator.
Life Science
 Indicator Examples from Food, Energy, and Growth - Example 1 Food, Energy, and Growth - Example 2 Food, Energy, and Growth - Example 3
Physical Science
 Indicator Examples from Chemistry That Applies - Example 1 Material A Chemistry That Applies - Example 2 Chemistry That Applies - Example 3 Matter and Molecules - Example 1 Material B Hard as Ice Matter and Molecules - Example 2 Material C Material D
Natural Selection and Evolution
 Indicator Examples from Material A Material B Material C Material D Material E Material F Material G Evolution Module - Example 1 Evolution Module - Example 2 Material H Material I Evolution Module - Example 3 Material J Material K