This article explains a simple way to demonstrate natural convection, such as from a lit candle, in the classroom using an overhead projector. The demonstration is based on the principle of schlieren imaging, commonly used to visualize variations in density for gas flows.

Describes how to produce a rainbow in the classroom using a laser and a large sphere, or a partial rainbow using a cylinder of water and a light source. (BR)

Describes an introductory lecture-demonstration for a physics class. The device transports a small steel ball from a starting point to a finishing point; along the way the ball goes through a number of steps. (RH)