Alaska Science
Key Element A5

A student who meets the content standard should understand the strength and effects of the forces of nature, including gravity and electromagnetic radiation (Forces of Nature).

Performance Standard Level 3, Ages 11–14

Students describe gravity as the force that governs orbital motion in the solar system and motion of the tides on the Earth, and describe light as radiation that travels in a straight line that can be reflected, refracted, or absorbed by matter.

Sample Assessment Ideas

• Students examine data on orbiting satellites and relate orbit size and period to velocity.

• Students make an Eskimo yo-yo and describe the similarity of its operation to the solar system, with gravitational force represented by the string.

• Students construct a model of the moon and Earth; use the model to demonstrate how high and low tides are formed.

• Students create a demonstration to show how a mixture of light of different colors can appear white.

Standards Cross-References
( Alaska Department of Education & Early Development Standards)

National Science Education Standards

Gravity is the force that keeps planets in orbit around the sun and governs the rest of the motion in the solar system. Gravity alone holds us to the Earth’s surface and explains the phenomena of the tides. (Page 161)

Light interacts with matter by transmission (including refraction), absorption, or scattering (including reflection). To see an object, light from that object—emitted by or scattered from it—must enter the eye. (Page 155)

Electrical circuits provide a means of transferring electrical energy when heat, light, sound, and chemical changes are produced. (Page 155)

The sun is a major source of energy for changes on the Earth’s surface. The sun loses energy by emitting light. A tiny fraction of that light reaches the Earth, transferring energy from the sun to the Earth. The sun’s energy arrives as light with a range of wavelengths, consisting of visible light, infrared, and ultraviolet radiation. (Page 155)

Benchmarks

Light from the sun is made up of a mixture of many different colors of light, even though to the eye the light looks almost white. Other things that give off or reflect light have a different mix of colors. (Page 90)

Every object exerts gravitational force on every other object. The force depends on how much mass the objects have and on how far apart they are. The force is hard to detect unless at least one of the objects has a lot of mass. (Page 95)

The sun’s gravitational pull holds the Earth and other planets in their orbits, just as the planets’ gravitational pull keeps their moons in orbit around them. (Page 95)

Electric currents and magnets can exert a force on each other. (Page 95)