Cloud in a Jar
What you need:
A Jar, some ice, hot water and hairspray
Step one: Fill half of the jar with boiling water. Then place the bottom of the cap on the jar.
Step 2 (hot and Cold)
Put ice on top of the jar and wait for 20 seconds.
Step 3 (Hairspray)
Quick spray with hairspray and recover.
Step 4 (Clouds)
Watch clouds form.