Inverted balloons

Balloon on flask.
It’s like a hat.

What can you do with a large Erlenmeyer flask, a kettle of boiling water, and a bag of balloons? Science, of course!

Get the flask hot with a pour of boiling water first, then pour out. Add a small amount of boiling water – as hot as can be – and quickly seal with a balloon. We’re looking for steam, and lots of it.

Then wait and see what happens!

Balloon in flask.
Cool!