- Two identical jars
- Hot water (you might need an adult to help you with this one)
- Cold water
- Index Cards (or a piece of another thick paper)
- Two colors of food coloring
- A plastic box (or something to catch the water that spills)
- Fill one of the jars with cold water and add a drop of food coloring. Look at what happens to the drop and then mix.
- Fill the other jar with hot water and add a drop of the other food coloring. Look at what happens to the drop and then mix.
- Make sure the index card or paper is big enough to cover the top of a jar.
- Add water to the cold jar until it is completely full and there is a bulge over the jar. (Want to know why this happens? It’s called surface tension! Try this experiment next: link to penny experiment)
- Cover the top of the hot water jar with the index card or paper. Using the index card to stop the water from coming out (watch out! This is tricky) pick up and flip the hot water jar so that it is upside down on top of the cold water jar.
- Have someone hold the jars while you slowly pull out the index card and watch what happens!