SCIENCE STRAND II:
PHYSICAL SCIENCE
Commonly thought of as physics and chemistry, physical science in this strand is limited to physical principles that can be observed and explored without complicated instrumentation or theories.
10. Explain the operation of a simple mechanical device.
“Simple mechanical devices” are simple, one-function machines that are reasonably familiar to fourth-grade students or that can be illustrated clearly. Students should be familiar enough with the six basic simple machines (lever, wedge, pulley, wheel and axle, inclined plane, and screw) to recognize them in real-world devices; recognize or explain how simple mechanical devices work (forces, motions, distances involved); and recognize how such a device can be used to reduce effort or force.
Students should understand that simple machines do not reduce work, but they commonly make an action less effort for people. Students should also know that the principle “you don’t get something for nothing” applies to simple machines: when a machine is used and the effort gets easier, something else (like speed, or the distance of the effort) is sacrificed.
11. Identify characteristics of a simple physical change.
Students should be able to identify characteristics or examples of a simple physical change— that is, a change in the size, shape (configuration), or state of matter of a substance, without its producing or becoming a new substance. Students should also be able to distinguish between changes that are physical only and changes that are chemical as well as physical; describe the energy flow or force that can cause a physical change; and identify properties of the different states of matter (gas, liquid, solid) that indicate a physical change. Items will employ real-world examples of physical changes (evaporation, condensation, melting, change in volume due to temperature, etc.).
12. Explain and/or predict the motion of objects and/or describe the effects of some objects on other objects.
Students should have a basic understanding of the concept of inertia; the relationship between mass, force, and inertia; gravity; friction, physical characteristics that are associated with causing or reducing friction, and the effect of friction on motion; magnetism; air pressure; and related forces or concepts. It is important that students not retain misconceptions about forces or concepts (e.g., the misconception that “since a nickel is heavier than a penny, gravity will make it fall faster”). Items will use real-world examples of objects with whose motions students are familiar.
Among the fundamental concepts students should understand are that things move only when something moves them; they keep moving until something stops them; the harder something is pushed, the faster it goes; and the more massive something is, the harder it is to move. Students who can best apply those concepts are those who have observed many moving things and investigated why they moved and how they may have been stopped.
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