Pinhole Camera Experiment

We gave each of the students a toilet paper tube, two rubber bands, a small square of both wax paper and aluminum foil, and a pin to create a small hole in the aluminum foil square to create pinhole cameras, which look like this:



We turned out the lights in the classroom and asked one group at a time to approach a lamp with their pinhole cameras pointed towards the light, and using their pinhole camera, to observe the image that is created on the wax piece of paper. Students observed an upside down image of the light bulb!



Next, we asked the students to think about why they saw the image of the light bulb upside down. They used the powerful ideas they had learned so far to help them determine how the light rays move through the pinhole cameras.
Light leaves its source in all directions.
Light travels in straight lines.

The students sketched the following diagrams to tell the story of how light rays travel though the pinhole camera.

Light leaves its source in all directions and travels in straight lines. Some of those rays in particular happen to leave the light source in such a way that they travel straight through the pinhole. Rays from the top of the light bulb travel straight through the pinhole to the bottom of the wax paper screen. Rays from the bottom of the light bulb travel staight through the pinhole to the top of the wax paper screen. Once those rays reach the wax paper, the image of the light bulb appears upside down. The light rays continue to travel in straight lines and reach someone's eye.

Powerful Idea: In order to see something, light must travel to the eye.