Test Tube Experiments and Visuals for Pre-Scool Ages, please?

Question

Test Tube Experiments and Visuals for Pre-Scool Ages, please?
I have test tubes, and want to know what to make with them. Something like the oil water mix experiment, sink/float tube, or whatever else you think I can do....I have 20 test tubes to make different visuals...so if you have any that you know will interest a child - PLEASE let me know,Thanks so much!

Answer 1

stuff some cotton wool in the bottom, plunk in a bean seed, add more cotton til the tube is 1/3 full, add water, watch the seed grow.

Please don't let the pre-schoolers play with the test tubes, though - they're dangerous in about 100 ways...