Oxygen in the Air


Magnetism has so many possible experiments associated with it that many megabytes of web-space could be devoted to the topic. Here is the simplest and perhaps the most valuable of all. Just hang a magnet on a long piece of string and it will always come to rest with one end facing North and the other end facing South.

Since magnets attract or repel each other, it's possible to get some idea of the extent of a magnetic field by holding a second magnet closer and closer to the first one until the first one begins to move slightly.

Oxygen in the air


The air around us is a mixture of Oxygen and other gases. Oxygen is needed for things to burn. By placing a glass or jar over candle in a basin of water, it is possible to see what fraction of the air is made up of Oxygen. As the Oxygen is used up, it's place is taken in the glass by the water.

When we breathe we take in Oxygen and breathe out Carbon Dioxide.