For work on volcanoes: Burn off the plastic and paint from a beer bottle top, place it in a fume cupboard, pile up a small ammount of ammonium dichromate and light the top with a bunsen burner (be careful not to set you hand alight, like I did the first time I did this!!). Watch that volcano go! It is fantastic, but because of the ammonium dichromate can only be demonstrated to the class (and you need to be careful with clearing up as well).

For work on volcanoes: Burn off the plastic and paint from a beer bottle top, place it in a fume cupboard, pile up a small ammount of ammonium dichromate and light the top with a bunsen burner (be careful not to set you hand alight, like I did the first time I did this!!). Watch that volcano go! It is fantastic, but because of the ammonium dichromate can only be demonstrated to the class (and you need to be careful with clearing up as well).

good fun demo modelling volcanoes: 500ml beaker, 1cm deep red candle wax in bottom, 1 cm clean sand on top, 400ml very cold water. Heat over tripod & gauze. Watch what happens. Don't forget the water represents the crust and not the ocean.