Shadow investigation turns the ubiquitous phenomenon of shadows into a systematic scientific inquiry. Why is the shadow the same shape as the object? Why does it change size? Why does it move? Each question has a testable answer children can discover through experiment. The investigation requires nothing but sunlight (or a flashlight) and objects — making it one of the most accessible science activities in early childhood.

Shadow Investigations to Try

• Trace your shadow: In the morning, have a partner trace your shadow in chalk. Return at noon and afternoon — where did it go? How did it change?
• Shadow puppets: Use hands against a flashlit wall — what shapes can you make?
• Size experiment: Move an object closer to and farther from a flashlight — observe how shadow size changes.
• Transparent vs. opaque: Which objects make dark shadows? (Opaque.) Which make faint ones? (Translucent.) Which make none? (Transparent.)
• Shadow color: Are all shadows the same shade? Observe shadows on different surfaces at different times of day.

Frequently Asked Questions

Why is a shadow the same shape as the object?

Light travels in straight lines. When an opaque object blocks the light, the light cannot bend around it — so the dark region behind the object matches the object's silhouette. If light could bend, shadows would be blurry and differently shaped. This straight-line travel of light is why shadows are sharp-edged in direct sunlight but softer (penumbra) in diffuse light — the multiple light directions from a large source create overlapping partial shadows at the edges.

Related activities: Build a Sundial | Rainbow Prism | Balloon Static Electricity