School is finally starting, but that doesn’t mean the wonder of summer has to end. Science experiments are a great way to explore the world around you – and for some schools an experiment for the science fair is mandatory. At a loss for ideas? We’re starting a new series of science experiments for you.
The Not-So-Magical Floating Paperclip
Have you ever gone for a walk with your child and stopped to visit a pond along the way? Often times, you’ll see small bugs skimming the surface of the water. These water striders understand something very important about the water they are standing on: Water molecules are STRONG. The molecules of water can cling tight to one another in order to hold something up. In nature, it could be a bug or small leaf on the surface of a pond. In your kitchen, you can show your child how strong water molecules are by floating a paperclip on it. You will need patience and a steady hand for this experiment … who will float the paper clip first: You or your child?
- Wide shallow cups
- Paper towels
- Dish soap
- Drop a paper clip into the water. What happens?
- Next, try to gently lay a paperclip flat on the surface of the water. If you are very careful you should be able to get the paper clip to float! Be patient!
- Now, touch a Q-tip onto the surface of the water an inch or two away from the paper clip. Does the paperclip move? Remove the Q-tip.
- Put a drop of liquid soap on the tip of the Q-tip and touch the surface of the water. Observe what happens!
What should happen?
When you first drop a paper clip in the water, it sinks. If you are steady and patient, you should be able to float a paper clip on the surface of the water but the addition of dish soap to your experiment will cause the paper clip to drop to the bottom.
Water is made up of MOLECULES just like a brick house is made up of bricks. The attraction of molecules towards one another is similar to the way a magnet is attracted to metal. Water molecules hold on very tightly to one another. The attraction of molecules towards one another at the surface of the water creates a sort of ‘skin’ that allows the paper clip to float. This is called SURFACE TENSION. When you added the dish soap, the bonds between the water molecules were broken which is why the paper clip sunk to the bottom of the cup.
Take it further:
There are many ways to study these concepts in more detail. Take a walk with your child and see if you can find bug on the surface of a pond that are taking advantage of the water’s surface tension. Or, you can see how many paper clips your water’s surface will hold before they all sink. Does the shape of the paperclip effect how it floats? Try different liquids like apple juice or milk. Which ones have the strongest surface tension?
Make science a hands on learning experience and your children will enjoy it!