Bouncy Ball Bonanza

Who doesn’t love a good bouncy ball? Though they were originally created out of natural rubber, these days they are made of plastics and other polymers or even treated leather. Using chemistry, you can make a bouncy ball of your own!

Vocabulary

1. Chemistry–
   (noun) a field of science that deals with the composition, structure, and properties of substances and with the changes that they go through.
2. Polymer–
   (noun) a chemical compound or mixture of compounds that is formed by combination of smaller molecules and consists basically of repeating structural units.
3. Solution–
   (noun) an act or the process by which a solid, liquid, or gaseous substance is dissolved in a liquid.
4. Scientific Method–
   (noun) the rules and procedures for the pursuit of knowledge involving the finding and stating of a problem, the collection of facts through observation and experiment, and the making and testing of ideas that need to be proven right or wrong.
5. Hypothesis–
   (noun) something not proved but assumed to be true for purposes of argument or further study or investigation.

Materials

• Borax (found in the laundry section of the store)
• Cornstarch (found in the baking section of the store)
• White glue (e.g., Elmer’s glue – makes an opaque ball) or blue or clear school glue (makes a translucent ball)
• Warm water
• Food coloring (optional)
• Measuring spoons
• Spoon or craft stick to stir the mixture
• Two small plastic cups or other containers for mixing
• Marking pen
• Watch with a second hand
• Metric ruler
• Zip-lock plastic bag

Activity

1. Label one cup ‘Borax Solution’ and the other cup ‘Ball Mixture’.
2. Pour 2 tablespoons warm water and 1/2 teaspoon borax powder into the cup labeled ‘Borax Solution’. Stir the mixture to dissolve the borax. Add food coloring, if desired.
3. Pour 1 tablespoon of glue into the cup labeled ‘Ball Mixture’. Add 1/2 teaspoon of the borax solution you just made and 1 tablespoon of cornstarch. Do not stir. Allow the ingredients to interact on their own for 10-15 seconds and then stir them together to fully mix. Once the mixture becomes impossible to stir, take it out of the cup and start molding the ball with your hands.
4. The ball will start out sticky and messy, but will solidify as you knead it.
5. Once the ball is less sticky, go ahead and bounce it!
6. You can store your plastic ball in a sealed zip-lock bag when you are finished playing with it.

Don’t eat the materials used to make the ball or the ball itself. Wash your work area, utensils, and hands when you have completed this activity.

Further Exploration

If you use the scientific method, you make observations before experimenting and forming or testing a hypothesis. You’ve followed a procedure to make a bouncing ball. Now you can vary the procedure and use your observations to make predictions about the effects of the changes.

• What happens when the diameter of the finished ball in changed? What about if it’s less sticky? How long it takes to solidify into a ball? How high can you make it bounce?
• Experiment with the ratio between the amounts of glue, cornstarch, and borax. Adding more cornstarch will make a ball that stretches and bends. Using less borax will produce a ‘goopier’ type of ball. Add more glue for a slimier ball.