In “Seasons Unraveled” (Activity Eight), students see how the concentration of sunlight striking the ground is affected by the angle at which the sunlight hits the ground. They then summarize the various elements they have found that help explain the causes of seasons. The fact that the Earth is a spinning globe, whose axis tilts with respect to its orbit around the Sun, gives rise to: (a) varying lengths of day in different seasons, and (b) variations in concentration of sunlight on the ground related to the angle that the light strikes the ground. With this complex understanding, they now are able to explain what causes seasons on Earth.

This movie shows how the light analyzer should be oriented with respect to the light source. When pointed directly at the light source, the shadow cast by the brad is minimal.	This movie shows how to use the light analyzer. It illustrates how the movable side, labeled “Ground” can be rotated to demonstrate how light spreads out. As the “ground” is tilted closer to the window, the light hits more directly, as it would in summer, when the Sun is high in the sky. As the ground is tilted away from the window, the light spreads out further, as it would in the winter, when the Sun is lower in the sky.

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