Always wear eye protection during science experiments. Never handle sharp objects, open flames, chemicals, or other dangerous objects without adult permission and supervision.
Note: this demonstration requires the use of a plastic water bottle. Make sure to recycle the empty bottle after you're done!
Trust me, this is going to be super cool. Supercooling is the process of lowering temperature of a liquid or gas below its freezing point, without it becoming a solid. This happens because a liquid needs what's called a seed crystal in order to start creating a solid.
In this demonstration, we're going to see how it's possible to supercool a liquid at home using little more than your freezer. When we've done that, we're going to check out the effect of adding a seed crystal, and believe me, this is the super coolest part of all.
Unfortunately, we have to start with a bit of waiting. Place the sealed water bottle into the freezer and wait for about an hour. Try your best not to move it too much or shake it after it's been in the freezer for some time, and don't forget about your bottle! If you leave it in too long it will simply freeze solid.
After the hour is (finally) up, take out your bowl and place an ice cube at the bottom of it. The frozen water molecules that make up the ice will act as seed crystals to help turn the supercooled water into ice.
Again, trying hard not to shake it, carefully take the bottle out of the freezer. At this point, the water inside it will be supercooled. Open the bottle and begin to pour it slowly over the ice cube in the bowl, and check out what's happening.