Cool, safe science experiments?

Hello,

For my Year 12 concert my friends and I are planning a performance to do with science. This will involve a bit of dancing to the song “I am a Scientist”, as well as experiments.

Experiments we’ve looked at are:
*Hot ice (building sculptures)
*Flame tests (if we are allowed)
*Elephant toothpaste (aka marshmallow experiment)
*Sodium in water (to be done at the very end when the “scientists” have left the stage – you know, a bit of a BANG to surprise the audience)

These are all well and good, but what we really need is something bright and spectacular, like fireworks or some form of glowing light. It doesn’t have to be an experiment, it could be something bought (though a bit more exciting than a party popper).

The biggest worry is finding something that is safe, and will impress a crowd of teenagers.

Any suggestions?