As motors go, this is about as simple as it gets.

A coil of wire becomes an electromagnet when current passes through it. The electromagnet interacts with a permanent magnet, causing the coil to spin. Voila! You have created an electric motor.

5 small disk or [...]

The attraction and repulsion of magnets produces entrancing, unpredictable motion.

Patterns of order can be found in apparently disordered systems. This pendulum – a magnet swinging over a small number of fixed magnets – is a very simple system that shows chaotic motion for some starting positions of the pendulum. The search for order in [...]

Making Waves

Hold a slinky between your hands, model transverse wave resonances as well as longitudinal wave resonances. Learn about nodes and antinodes of motion and compression.

A slinky
2 chairs
about 3 meters of 20 pound test monofilament fishing line
Optional substitute for nylon line, a smooth [...]

One reason not all buildings are equal in an earthquake.

This device graphically demonstrates that objects of different sizes and stiffnesses tend to vibrate at different frequencies.

A sheet of cardboard measuring 1 foot (30 cm) long and several inches wide.
A large sheet of construction paper (about 14 x 20 inches [...]

Who needs expensive optical equipment?

A pinhole in an index card can act like a magnifying glass, helping your eyefocus on a an object that is very close to you. However, by limiting the amount of light that reaches your eye from the object, the pinhole also makes the object appear dimmer.

A 3 x 5 [...]