Ethanol combustion can be done safely. Watch out for flying nails.

Use very small amounts -- VERY small amounts of sodium when demonstrating the reaction of sodium with water.

Three demonstrations can be used to illustrate saftey issues. Consider the maturity of your class before demonstrating these; there are NOT things for kids to try themselves. Methane-air mixtures can explode. Rising methane burns; methane mamba. Show a dust explosion, as happens when grain is stored.

Show electronically; don't do these.

The ammonium dichromate volcano used to be very popular, but is done much less often because of the problems with chromium.

The thermite reaction is widely used as a dramatic chemical demonstration. This reaction is dangerous. There have been at least two different incidents connected with the University of Illinois. In one, a very large motorized screen was consumed in flames when sparks from the reaction caught the screen on fire. In the other, the molten iron was caught in water -- and the beaker exploded sending glass shards into an audience of young onlookers. An alternative of this dramatic demonstration involves taking two large iron spheres, wrapping one with aluminum foil, and striking the spheres together.

Nitrogen triiodide is very sensitive. Just touching the dry crystals causes explosion. This can be very dangerous.

Peroxyacetone has maimed many chemistry teachers.