Bouncy Ball Science Experiment

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Bouncy Ball Science Experiment

This bouncy ball science experiment is a fun way to see if you can make a homemade bouncy ball. When I first tried this experiment, I was a little disappointed to find that it doesn’t make a firm ‘ball’ that will hold its shape for a long time, and it is not bouncy like a typical rubber ball. If just left to sit for a short time, this ball will flatten and lose its shape. It is quite similar to making borax slime but with a firmer texture. However, there are some excellent reasons to try this out. It is a quick and easy experiment that children will enjoy helping with, and then they can enjoy playing with the results. You can also challenge children to see if they can change the proportions of the ingredients to create a ball that has more bounce.  

My children love playing with balls, and this is a fun way for them to make their own. Unfortunately, as noted above, these balls are temporary, and they also begin to dry out and lose their bounciness/elasticity over several days. To help them last longer, it’s a good idea to store them in a sealed bag.

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How it works

Glue consists of long chains of molecules known as polymers which easily slide past each other to create a liquid. When the glue and borax combine, the borax acts as a ‘cross-linker’, sticking the glue’s polymers together so they cannot move around so easily. This new substance is known as an elastomer. Elastomers are flexible and rubbery, so they cause the ball to squish and bounce back when it hits the ground. The corn starch helps bind the molecules together to help hold its shape even more than is the case with regular slime.

**You can think of polymers (glue) like freshly cooked spaghetti. They are long, slippery and slimy and easily slide over each other. When the glue combines with borax to become an elastomer, it is like when pasta begins to dry out, stick together and become rubbery.  

What you need for Bouncy Ball Science Experiment

Ingredients

• Borax
• Cornflour / corn starch
• Glue (You can use clear glue for a transparent ball or white glue to make an opaque ball)
• Small cups or bowls for mixing
• Measuring spoons
• Stirring stick, lolly stick or plastic spoon
• Food colouring (optional)
• Glitter (optional)

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Instructions

You will need one cup/bowl to make the borax solution and another to make the ball mixture. If you have premade borax solution (such as from slime kits), you will not need the extra cup and will skip the borax solution making step.

Pour 120ml (4 ounces) warm water into the cup to be used for the borax solution. Put 1 teaspoon of borax powder into the cup and stir it until the borax completely dissolves. ***Alternatively, you can use premade borax solution, but note that you may need more of it to achieve the same recipe.

Pour 1 tablespoon of glue into the other cup (ball mixture). If you want, you can several drops of food colouring and mix into the glue (optional).

Measure ½ teaspoon of the borax solution and 1 tablespoon of cornflour (corn starch) and add both of them to the glue. *Wait to stir.*

The ingredients need to interact for approximately 10-15 seconds, after which time begin stirring until they are thoroughly mixed.

When the mixture becomes too hard to stir, remove it from the cup. Finally, mould the ball with your hands. Initially, it will be very sticky, but over time it will come together and solidify. Continue to roll it between your palms until it is round and smooth.

*Keeping the ball wrapped in cling film or a bag will help it last longer.

Safety advice

Borax (sodium tetraborate) is sometimes used as a cleaning product and can is in a range of household products. However, it can cause side effects such as irritation to eyes and skin but can also be toxic and deadly if ingested. For that reason, if you are going to do this experiment with children, you should do so with caution. When we did this experiment, I mixed up all the ingredients, and then my children played with the results. I didn’t let them help as they are very young. I also supervised them when they were playing with the bouncy balls. You may let older children help make the balls, but they need to be supervised by an adult at all times. I would also recommend safety goggles or glasses.

Questions to ask

• What happened when you combined the ingredients? When you mixed them? What did you notice?
• How did the ingredients change?
• How high can you make your ball bounce?
• Is there a way to make it bounce higher or lower?  
• Does the surface you bounce it on change how high it bounces? Does how hard you throw it or how high you drop it from above change how high it will bounce?
• Can you find a way to make your ball last longer?
• Can you change the recipe to make the ball more or less bouncy?  
• What happens when you use more cornflour? Less?

What they get from it

If children like making slime, this is a fun way to see how the recipe can be changed to make something slightly different. 

Children can practice inquiry by creating an experiment. They can change different factors to compare and discover how it changes the balls.  

Take it further

Children can try adjusting the recipe to see if they can make a bouncier ball. They may try using different amounts to see how changes in each ingredient affect the outcome.  Can they make an experiment and test a hypothesis – Can they figure out a way to make a bouncier ball? What makes the ball more or less bouncy?

Children can try bouncing a ball on different surfaces, from different heights, and throwing with different forcefulness, etc. to see how these factors affect the bounciness.  

If children enjoy the texture, they might want to try making slime. They can try traditional borax recipes, or I also have some chemical-free and edible slime recipes such as Slime with Starch (coming soon), Psyllium Slime (coming soon) and Tapioca Pearl Slime (coming soon).

You may also want to see some of my other STEM activities such as Homemade Bath Bombs for Kids or Color pH Baking Soda and Vinegar Science Experiment.