A shadow appears when an object blocks light. That simple idea becomes an experiment when a child changes one thing and looks again. A flashlight, a small toy, and a plain wall are enough to make light and shadows visible without special equipment.
Set up a clear light–object–wall line
In a dim room, an adult holds a flashlight facing a blank wall. Place a solid toy between the light and wall. Move the toy until its shadow has a clear outline. Keep the beam away from anyone's eyes, use an ordinary low-heat flashlight, and do not use a laser pointer. The child can point to the toy and its shadow and describe what looks the same or different.
Try these words in context: light source, object, shadow, nearer, farther. You do not need a long science lecture. Ask the child to predict: “What will happen to the shadow if the toy moves closer to the flashlight?”
Experiment 1: Change the distance
- Keep the flashlight and wall in the same places. Put the toy close to the wall and notice its shadow size.
- Move only the toy toward the flashlight. Compare the outline on the wall.
- Move it back toward the wall. Ask what changed and what stayed the same.
In a typical setup, a toy nearer the flashlight makes a larger shadow on the wall. If the shape becomes fuzzy, reposition it until the edge is visible. Encourage the child to describe what they actually see, even if the result differs from their prediction.
Experiment 2: Change the direction
Hold the toy still and move the flashlight a little to one side. Does the shadow move to the same side? Try the other direction, then let the child explain what happened. Change just one thing at a time so the comparison is meaningful. If the child moves both light and toy, reset and try again rather than calling their experiment wrong.
Experiment 3: Which objects cast a visible shadow?
Compare a solid toy, a sheet of plain paper, and a clear plastic container. What can you see on the wall for each? Thin or transparent materials may give a weaker or different-looking shape. Invite a prediction, test it, and discuss the result. Keep breakable items and small parts out of the activity for young children.
Make a record
Trace one shadow on paper taped to the wall while the toy stays still, or ask the child to draw the two sizes they observed. Label the drawings “closer to light” and “closer to wall.” A single before-and-after comparison is enough evidence for a preschool investigation.
A sample conversation
Adult: “The toy is close to the wall. How big is its shadow?” Child: “Small.” Adult: “What do you predict if I move the toy toward the flashlight?” Let the child point to the expected size with their hands, then move only the toy. Adult: “What happened? Was it what you expected?” If the child predicts something else, the observation still gives you something to discuss.
Afterward, put the flashlight behind the child and let them see their own shadow on the wall from a comfortable distance. Ask what changes when they raise one hand. Never shine the flashlight into a face. Return to the toy for a fair size comparison, because a moving child changes more than one variable at once.
Why a shadow can become fuzzy
A broad light source, translucent object, or an object far from the wall can make an edge less distinct. This is another observation to investigate: “Can we make the outline clearer by moving only the toy?” Try a solid toy first, then compare. Do not promise that every object's shadow will look like an exact black copy; real light and materials make more varied results.
NASA's Bear's Shadow activity also uses a flashlight and an object to explore how shadows change. For another question-led investigation, see our simple science experiments at home. Our weather and seasons guide offers outdoor observations for another day; never look directly at the Sun during outdoor shadow play.