I call students to the gathering area and we review our data from the last lesson on detecting motion and color. We talk about the fact that although our eyes seems to see in many directions at once, their eyes themselves, only see things at certain points. I ask students to think about how it is then that we are able to see all around?
I ask students how the eye is attached to the body. Students come up with tendons and muscles. Usually someone comes up with the thought that the eye is also connected to the brain through the optic nerve.
I tell students that to simulate how the eye and brain work together, we will make a pinhole camera. I do not discuss what a pinhole camera does or how it works. I want students to build it and discover it, and then we will discuss it.
Students follow the handout and build a pinhole camera for every four students. They test it, and record their observations, but do not share their results with other groups until we come back together as a whole class.
As students complete the pinhole camera and test it, I also give them reflection question to answer. Students bring these to the whole-group discussion to help answer the questions.
If the pinhole camera works the same way as your eye, how do you see things the right way up?
I call students back to the gathering area, with their observations and reflections. We work through their observations first. I then ask them to share the answers to their reflection question. We discuss that the brain does a lot of interpretation in order for us to see the whole picture around us. Our brain fills in the color in our peripheral vision, and it turns objects the right way up so we perceive the world as it is around us. I want students to understand that the eye does not function in isolation, but is directly connected to the brain that processes the images and makes sense of them for us.
If students get done earlier than others, I let them go to optical illusions and play with optical illusions. This is a fun addition to the class discussion as we can talk about how what we “see” can change depending on how our brain interprets it.