Pop Top- Science Experiment

So, my Kinders like LOVE science experiments.  Here's one of their favs:  Pop Top :)

Here's how you do it:
- Fill a film canister (you know, the ones from the 80s)  :) with water.
- Put 1/2 a tablet of Alka-Seltzer in the water.
- QUICKLY put the lid back on top of the canister.
- Step back.
- In about 5 seconds, the top will go FLYING off with a loud "pop"!!

Don't forget to put a tray or something down because occasionally the canisters will fall over!

What you learn:  REACTIONS!  Water and Alka-Seltzer tablets form a reaction in the form of bubbles!    Pressure builds up and the top finally pops off releasing the built up pressure!

If they are well-behaved through the experiment and keep safety first (meaning-- DONT point your canister at someone when it's about to pop), I surprise them with a 10 canister POP extravaganza!  They LOVE LOVE LOVE it! :) 

This one (and our Diet Coke and Mentos experiment) are their favs.

Science can be FUN! :)

What is your students' favorite classroom activity??