Skip to Main Content

Cardboard Tube Syllabus


Cardboard Tube Syllabus

Grade Levels

10th Grade, 5th Grade, 6th Grade, 7th Grade, 8th Grade

Course, Subject

Science and Technology and Engineering Education, Science
Related Academic Standards

Content Provider


With these tubes, you can perform a variety of experiments. Each has its own "To Do and Notice" and "What's Going On." Try all four!
  1. Hole in your Hand
  2. Overlapping Spots
  3. Circles or Ovals?
  4. Lateral Inhibition

Hole in your Hands

To Do and Notice

Take one of the tubes that you made from a full sheet of paper in your right hand. Hold it up to your right eye and look through the tube, keeping both eyes open.

Now put your left hand, fingers up, palm toward your face, up against the left side of the tube, about two-thirds of the way down. Notice that you see a hole in your hand.

What's Going On?

One eye sees a hole, the other sees a hand. Your eyes and brain add the two images together, creating a hand with a hole in it!


You have two eyes, yet you see only one image of your environment. If your eyes receive conflicting information, what does your brain do? Do receptors in the eye act independently, or do they influence each other? By looking through some simple tubes made from rolled-up pieces of paper, you can explore how your two eyes influence each other.


  • A well-lit white screen, white wall, or white sheet of paper.
  • Several sheets of white paper, such as typing paper or photocopy paper.
  • Transparent tape.


10 - 20 minutes


Roll three of the sheets of paper into paper tubes that are 11 inches (28 cm) long and about 1/2 inch (1.3 cm) in diameter. Use tape to keep the tubes from unrolling. Squash one of the tubes so that its cross-section is a very flat oval.

Cut one piece of paper into a strip that is about 2 1/2 inches (6.4 cm) wide and 11 inches (28 cm) long. Roll this strip into a tube that is about 1/2 inch (1.3 cm) in diameter and 11 inches (28 cm) long.

Content Collections

Overlapping Spots

To Do and Notice

Take two round tubes that you made from full sheets of paper. Put the tubes up to your eyes and look through them at the white screen, wall, or sheet of paper. First close one eye, and then open it and close the other. Does the brightness of the spot appear the same for each eye?

Move the tubes to overlap the two spots. Notice that there is a brighter area where the two spots overlap.

Overlap the spots completely. Does the combined spot look brighter than either spot alone? Find out by closing one eye.

What's Going On?

When you partly overlap the two spots, your open eye and brain conclude that the sum of the two spots of light should be brighter than one spot alone. If the spots overlap completely, the brain seems to ignore one of them.

Circles or Ovals?

To Do and Notice

Hold one of the round tubes up to one eye and the tube that you flattened up to the other eye. Look through the tubes at the white screen, wall, or paper. Overlap the spots. Do you see the circle or the oval? Switch the tubes and repeat. If you saw only the circle before, you may see the oval now.

What's Going On?

Your eyes and brain have trouble merging the different shapes. Most people have a dominant eye. The brain will choose to see the image that is coming from the dominant eye. Some people do not have a dominant eye, and therefore see the two shapes overlapped. The best baseball hitters do not have a dominant eye.

Lateral Inhibition

To Do and Notice

With both eyes open, look at the white screen, wall, or paper through one of the tubes you made from a full sheet of paper. Notice that the spot of light that you see through the tube appears brighter than the wall of the tube.

Do the same thing using the tube that you made from a narrow strip of paper. Notice that the spot appears darker than the wall of the tube.

What's Going On?

When light receptors in your eyes receive light, they send a signal to your brain. A receptor receiving light also sends signals to neighboring receptors, telling them to turn down their own sensitivity to light. When you look at the white wall without a tube, you see a uniform field of brightness because all the receptors are equally inhibited. When you look through the tube that you made from a full sheet of paper, the spot of light is surrounded by the dark ring of the tube. The spot appears brighter because the receptors in the center of your retina are not inhibited by signals from the surrounding dark ring.

In contrast, light shines through the walls of the tube that you made from a strip of paper. When you look through this thin-walled tube, the spot appears darker because light comes through the wall of the tube, causing the receptors at the center of your retina to be inhibited. This is known as lateral inhibition.


You can use paper towel tubes for all but the last of these experiments.
Please wait...

Insert Template