The text asserts the key ideas without developing an evidence-based argument to support them.

The key ideas are treated mostly as isolated pieces of information in chapters that are organized around topics, rather than around a coherent set of physical science concepts. Although the text occasionally mentions that students have had experience with an idea—for example, before defining temperature as the measurement of the average kinetic energy of the molecules in a substance, students are asked to “Recall that all matter is made up of molecules that are in constant motion” (p. 209s)—this is not done systematically, nor are the experiences described specifically. For instance, the idea that increased temperature means greater molecular motion appears in several places. In chapter 6, this idea comes up in the context of Charles’ Law; in chapter 9, it is used to explain the thermal expansion of liquids in thermometers in the discussion of measuring temperature; later in the same chapter, it is used to define and explain thermal expansion in general and to give examples of thermal expansion. However, no connections are made between these instances.

Like every chapter in Science Insights: Exploring Matter and Energy, the chapters that are related closely to the kinetic molecular theory include numerous features (e.g., Themes in Science, Integrating the Sciences, STS Connection) that are intended to integrate the sciences, connect science to other disciplines, and integrate science, technology, and society (p. T–35). However, the connections to be made do not contribute to students’ understanding of the key physical science ideas. For example, some features simply emphasize labeling various phenomena as physical changes (e.g., pp. 147t, 148t).

In other cases, the connection that the material tries to make is contrived and relates only tangentially to the content of the section. For example, in a section on the properties of gases and their explanation at the molecular level, the text states in Integrating the Sciences that during photosynthesis, plants release oxygen [a gas] into the air and suggests that students see bubbles of oxygen forming on plant leaves in an aquarium (p. 142s).

The evaluation teams developed a summary assessment of the most common kinds of errors found in each of the three subject areas—physical science, Earth science, and life science. In this context, “errors” is taken to mean not only outright inaccuracies, but also those instances in which the material is very likely to lead to or support student misconceptions. Overall, inducement to misconstrue is the most serious problem of accuracy in the evaluated materials.

The evaluation teams’ collective findings, presented below, should be taken as having general applicability to all of the evaluated materials, not complete and specific applicability in toto to any one of them.

Identified errors occur most frequently in drawings and other diagrams. They take the form of representations that are likely to either give rise to or reinforce misconceptions commonly held by students. Following are physical science examples of the kinds of misleading illustrative materials of most concern to the evaluation teams:

• Diagrams and drawings that show atoms or molecules of solids, liquids, and gases in colored backgrounds (for example, water molecules inside blue drop shapes) and that thereby can initiate or reinforce the misconception that particles are contained in solids, liquids, and gases, in contrast to the correct idea that substances consist of particles (with empty space between particles). This misconception may be further reinforced by the wording of diagram labels, such as “solid particles in solid water and water particles in liquid water” (emphasis added). Similarly, statements such as “explanations for what is inside things” may imply that matter contains particles (as well as other things), rather than that matter is made of particles.

• Diagrams of solids (and occasionally liquids) that do not depict the motion of atoms or molecules can give rise to, or reinforce, the misconception that atoms or molecules of solids (or liquids) are still.

• Diagrams that show molecules of liquids much farther apart than the molecules of solids are misleading; in most liquids, molecules are only a little farther apart.

• Diagrams that show particles of a substance in the solid, liquid, and gaseous state in different colors can reinforce the erroneous idea that the particles themselves are different, not their arrangement and motion. Similarly, diagrams that show particles of a substance changing size as the substance changes state can give rise to the misconception that the molecules themselves change size, becoming larger when heated.

The use of imprecise of inaccurate language is problematic in text materials, not solely in illustrations. Specifically, language that does not maintain a clear distinction between substances and atoms or molecules can mislead students to attribute macroscopic properties or behavior (such as hardness, color or physical state) to individual atoms or molecules. For example, statements such as “the particles of perfume are moving farther apart as they change into a gas and diffuse throughout the air,” “write a story from the point of view of a particle in the solid phase as it melts and then evaporates,” and “draw what happens when the particles change state” (emphasis added) imply inaccurately that the particles themselves change state (melt, evaporate, etc.).