by Martin Gardner in Games Magazine February 2007
When your toilet paper rolls run out of paper, don’t throw away the cardboard tubes.
Here are seven amusing things you can do with them:
1. A Betcha
Bet someone who he or she can’t hold the tube six inches above a table and drop it so it lands upright and remains standing on one end. After repeated failures, you show the only way it can be done: Hold the tube horizontally before you drop it. You may have to do this more than once, but after a few tries the tube will balance upright after landing.
2. An Optical Illusion
Believe it or not, the tube’s Circumference is longer than its length. A quick way to prove this is to cut the cylinder apart lengthwise, then open it into a rectangle. One side of this rectangle is the tube’s circumference. The other side is the tube’s length. A ruler will prove the surprising fact that the circumference is almost a full inch longer than the length!
3. A Paradox
Place two tubes side by side, then balance a yardstick across them. If you rotate the tubes inward in opposite directions, the yardstick will stay balanced. Now try rotating the tubes the other way. The yardstick will slowly travel to one side until it falls off the tubes. Why does the direction of rotation make such a big difference?
4. Hole in Your Hand
Hold up your left hand, palm toward you. With your other hand, place the tube alongside your palm. Peek through the tube with your right eye, keeping both eyes open, and stare at a distant spot. You’ll be looking through a large hole in your left hand.
5. A Mysterious Force
Two tubes are alongside each other on a table. Rub your hands vigorously together to generate a psychic force. Place your hands palms down fingers pointing toward the tubes. Lower your head slightly. Move your hands slowly away from the tubes, and at the same time secretly blow on them. They will roll toward your hands as if drawn by a mysterious attractive force. You’ll be surprised at how many people will be totally mystified by this simple trick.
6. Unbreakable Tissue
With a rubber band, attach a piece of tissue paper over one end of the tube. With the tube vertical, fill it to the top with uncooked rice.
Using a thumb or finger, press as hard as you can on top of the rice. Amazingly, you’ll find it impossible to break the tissue!
7. A Kazoo
Attach a piece of wax paper over one end of the tube, using a rubber band. Near the other end make a small hole in the tube’s side. With your lips around the hole, hum a tune. You’ve made a kazoo!