# Test Surface Tension

Have you ever noticed that when it rains, water forms as droplets on surfaces instead of spreading out? This is because of surface tension. See water surface tension in action using coins!

Time: 20 minutes

Materials: different types of coins, paper towels, pipette or eye dropper, cup of water, pencil and paper, soap (optional), spoon (optional)

Steps:

1. Collect different types of coins.
2. Place each coin on a paper towel. Your goal is to see how many drops of water a coin can hold.
3. Guess which coin will hold the greatest number of drops. Write down your guess on a piece of paper.
4. Gather a pipette or eyedropper and a cup of water. Fill the pipette with water. Using the pipette, squeeze out the water, one drop at a time, onto the surface of a coin.
5. Continue to add drops of water onto the coin. Notice how the water starts as a tiny droplet and gets bigger as more drops are added. Eventually, it forms a dome.
6. Count the total number of drops on the coin until the water spills over. Write down the total number of drops for each coin.
7. Repeat the process for each coin.