"Do water molecules really move? If so, how fast and how slowly?
You will need:
2 clear glasses
cool and hot tap water
What to do: Fill one glass with cool tap water. Fill the other glass with hot tap water. Now, quickly place one drop of food coloring in each glass. (Make certain that all of the variables are the same. This means the glasses should have the same amount of water in them and that the same number of food coloring drops are added. Controlling variables is important to make the experiment scientifically correct.)
What happens: The food coloring spreads throughout the water in both glasses, but at different rates.
Why: The cold water eventually becomes completely colored because the water molecules are moving throughout the glass. But when the water is warmer (the hot tap water), the heat energy in it causes the water molecules to move much faster. This makes the food coloring spread out more rapidly. You might want to chart, or keep a record of, how much time it takes for the food coloring to spread evenly throughout each glass of water."
What happened when CKS tried it? We used boiling water and cold water from the fridge. The hot water spread first and the cold water spread last. It took the hot water 1 minute and 4 seconds, and the cold was 2 minutes and 33 seconds.
CKS rating: 3 stars - Good but not that good