This experiment models how the Sun’s angle affects the distribution and intensity of sunlight on Earth’s surface. By shining a flashlight on grid paper at different angles, students observe that light becomes more spread out and less intense as the angle decreases, explaining why regions near the equator are warmer than those near the poles.

1. Gather materials: flashlight, grid paper, protractor, pencil, tape, and several books.
2. Tape a sheet of grid paper to the cover of a book so it stands vertically.
3. Stack books on a table and place the flashlight on top to elevate it.
4. Turn off room lights to create a dark environment.
5. Position the flashlight so its beam shines directly (90°) onto the grid paper.
6. Trace the illuminated circle on the paper with a pencil and count the number of grid squares lit by the light, estimating partial squares if needed.
7. Repeat the experiment with the flashlight tilted at different angles (e.g., 45° and 30°).
8. For each angle, trace the illuminated shape and count the number of squares covered.
9. Record observations for each angle.

Angle of insolation lab - Urfsigns Schweizer:

• Use a light sensor or thermometer to measure actual light intensity or temperature differences at each angle.
• Try more angles (15°, 60°, etc.) for a complete data set.
• Compare results using different light sources or distances from the paper.
• Graph lighted area (in squares) versus angle to visualize the relationship.

• Avoid shining the flashlight directly into anyone’s eyes.
• Supervise students while working in the dark to prevent tripping or equipment damage.

• How does the shape of the illuminated area change as the angle decreases? (It becomes larger and more stretched out.)
• Why does the 90° angle create a more intense light spot? (The same amount of light energy is focused on a smaller area.)
• What does this model tell us about sunlight at the equator versus the poles? (Sunlight at the equator is more direct and concentrated, producing higher temperatures; sunlight near the poles is angled and spread out, resulting in cooler temperatures.)
• How does this experiment relate to Earth’s seasons? (As Earth tilts, the Sun’s rays strike at different angles throughout the year, causing seasonal temperature changes.)
• How might this concept affect solar panel efficiency? (Panels work best when positioned to receive light as directly as possible.)