Tuesday, July 29, 2014

The Pinhole Investigation

The Pinhole Investigation is a very simple activity, but very affective to make students understand and confirm for themselves that the image that comes through a pinhole is reversed from top to bottom and left to right. This activity will provide our students with an opportunity to think and discuss why images appear in reverse, from top to bottom and left to right.
To make a pin hole, we need a sheet of black construction paper, 1 cardboard toilet tissue tube, 1 piece of aluminum foil, 1 piece of wax paper, and 4 rubber bands.
How to make
I will share how I made my pinhole at The Exploratorium Summer Institute Teacher Training Program. I placed the aluminum foil over one end of the toilet tissue tube and secured it with a rubber band. Then I placed the wax paper over the other end of the toilet tissue tube and secured it with a rubber band. Here we were instructed to be careful with the wax paper to keep it as smooth as possible because it is a screen.
Next, I rolled the black construction paper lengthwise around the tube, keeping the aluminum foil end exposed. The wax paper end of the tube became the middle of the black construction paper tube. Later, I came to know that the black tube has its purpose to allow us to see the images more clearly.
Finally, I used a pin to make a hole in the aluminum foil. We were told that sometimes the hole must be enlarged to see the image more distinctly, but it was better to start with a small hole and then make it larger if needed.
What next?
After making a pin hole, each student can take the viewer outside and look at houses, trees, cars, etc. through the open end of the tube. Ask this question to students: What do you notice?
We tried the viewer inside the classroom looking at one red and one green light bulb. We can also try it with a candle.
The following were a few questions we discussed in the class, and we can ask similar questions with the students: Why is the image reversed? How can I make it turn right-side up? How can I make the image clearer? How can I make the image larger? What if I used a larger tube, a longer tube, a larger hole, etc.?

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