AAAS Project 2061 Middle Grades Science Textbooks Evaluation
Key Ideas Used for the Evaluation
Physical Science Topic: Kinetic Molecular Theory
Ideas that served as the basis for the analysis were drawn from Chapter 4, Section D of Benchmarks for Science Literacy and from Physical Science Content Standard B of National Science Education Standards
- All matter is made up of particles called atoms and molecules (as opposed to being continuous or just including particles).
- These particles are extremely small--far too small to see directly through a microscope.
- Atoms and molecules are perpetually in motion.
- Increased temperature means greater molecular motion, so most materials expand when heated.
- Differences in arrangement and motion of atoms/molecules in solids,
liquids, and gases:
- In solids, particles (i) are closely packed, (ii) are [often] regularly arranged, (iii) vibrate in all directions, (iv) attract and "stick to" one another.
- In liquids, particles (i) are closely packed, (ii) are not arranged regularly, (iii) can slide past one another, (iv) attract and are loosely connected to one another.
- In gases, particles (i) are far apart, (ii) are randomly arranged, (iii) spread evenly through the spaces they occupy, (iv) move in all directions, (v) are free of one another, except during collisions.
- Explanation of changes of state--melting, freezing, evaporation, condensation, and perhaps dissolving--in terms of changes in arrangement, interaction, and motion of atoms/molecules.
- Connection between increased temperature and increased energy: Increased temperature means greater average energy of motion, so most substances expand when heated.
Life Science Topic: Transformation and Transfer of Matter and Energy
Ideas that served as the basis for the analysis were drawn from Chapter 5, Section E of Benchmarks for Science Literacy and from Life Science Content Standard C of National Science Education Standards
- Food (for example, sugars) serves as (molecules that provide) fuel and building material for all organisms.
- Plants make their own food, whereas animals obtain food by eating other organisms.
- Matter is transformed in living systems:
- Plants make sugars from carbon dioxide in the air and water.
- Plants break down some of the sugars they have synthesized back into simpler substances--carbon dioxide and water--and assemble some of the sugars into the plants' body structures (including some energy stores).
- Other organisms break down the stored sugars or the body structures of the plants they eat (or in the animals they eat) into simpler substances and reassemble them into their own body structures (including some energy stores).
- Decomposers transform dead organisms into simpler substances, which other organisms can reuse.
- Energy is transformed in living systems:
- Plants use the energy from light to make "energy rich" sugars.
- Plants get energy by breaking down the sugars, releasing some of the energy as heat.
- Other organisms get energy to grow and function by breaking down the consumed body structures to sugars and then breaking down the sugars, releasing some of the energy into the environment as heat.
- Matter and energy are transferred from one organism to another repeatedly and between organisms and their physical environment.
Earth Science Topic: Processes that Shape the Earth
Ideas that served as the basis for the analysis were drawn from Chapter 4, Section C of Benchmarks for Science Literacy and from Earth and Space Science Content Standard D of National Science Education Standards
- The (seemingly solid) earth is continually changing (not only has it changed in the past but it is still changing).
- Several processes contribute to building up and wearing down the earth's surface.
- The processes that shape the earth today are similar to the processes that shaped the earth in the past (not comparing rates).
- Some of the processes are abrupt, such as earthquakes and volcanoes, while some are slow, such as continental drift and erosion.
- Slow but continuous processes can, over very long times, cause significant changes on Earth's surface (e.g., wearing down of mountains and building up of sediment by the motion of water).
- Matching coastlines and similarities in rocks and fossils suggest that today's continents are separated parts of what was long ago a single vast continent.
- The solid crust of the earth consists of separate plates that move very slowly, pressing against one another in some places, pulling apart in other places.
- Major geological events, such as earthquakes, volcanic eruptions, and mountain building, result from these plate motions.