Toys and Trinkets
Toys have been used successfully to demonstrate principles of physics. Most inspiring physics teachers have their pet toys hidden away in drawers, cabinets and pant pockets. They include things like the dunking bird, gyroscopes, yo-yo's, a tippy-top, propeller on a notched stick, Newton's cradle, slinky and coupled pendulums. Most toys have an advantage over conventional demonstration equipment in their relatively low-cost and the fact that children relate well to them. Unfortunately most toys are not made for repeated use and that they are often no longer available when one looks for replacements!
Some traditional toys can be used to great advantage in a science class. It is unfortunate that science teaching ignores traditional toys. The Joy of Making Indian Toys by Sudarshan Khanna, documents over a hundred toys which have been made by Indian children for generations - much before sexist and violent toys like the Barbie and Skull Man made their debut. Traditional toys are R & D for hundreds of years. Generations of children have made them and perfected them. The Sudarshan Chakra is a classic example. It is made from a coconut broomstick, some thread and an injection bottle rubber cap. It costs almost nothing and can be used to demonstrate the force of rotation. Every child - even the poorest could afford and play with it.
The Notched Pencil - another traditional toy has now become a darling of science teachers. It can be made in less than five minutes. You just have to make a few notches on a pencil. Then insert a card fan on a paper pin at the end of the rubber. If you now rub the notches with an old ball pen refill the fan magically rotates! Many people think that it has to do something with airflow or static electricity. Far from it. This toy is based on vibrations. The physics behind it is non-trivial and quite sophisticated. Several learned research papers have been written on the working of this toy.