Bouncy Ball

We made our own bouncy balls last week.  The bouncing ball in this activity is made from a polymer. Polymers are molecules made up of repeating chemical units. Glue contains the polymer polyvinyl acetate (PVA), which cross-links to itself when reacted with borax.  To make a bouncy ball, you need:

• 1/2 tsp Borax powder
• food coloring
• 1 TBSP glue
• 1 TBSP cornstarch
• 2 disposable cups

Directions:

1. Pour 2 TBSP warm water and 1/2 tsp Borax powder into a disposable cup
2. Stir until the powder is dissolved
3. Add food coloring as desired
4. Pour 1 TBSP glue (we used regular Elmer's glue) into a separate disposable cup
5. Add 1/2 tsp of the borax solution you made to the cup with the glue - do not stir
6. Add 1 TBSP cornstarch to the glue/borax solution - do not stir
7. Allow the ingredients to interact on their own for 15 seconds, and then stir to fully mix the ingredients
8. Once it is impossible to stir, take it out of the cup and mold it with your hands
9. It starts out sticky and messy, but solidifies as you knead it
10. Once the ball is less sticky, you can bounce it.
11. Store it in a sealed plastic bag

We found these exact same directions on many different websites, but Science Bob is where I first saw the idea.  The balls don't bounce very high on the hard floor.  I expected them to bounce well, and so did C and R, so this was a bit of a disappointment.  C and R had the most fun just throwing the balls.

To make this into more of a science experiment, you can alter the amount of borax, glue, or cornstarch and record your results.  From what I read, you should keep the amount of water consistent.

I tried to get pictures of them bouncing/throwing their balls, but I had no luck.  I ended up with a bunch of pictures of the kids making weird hand motions.  

I am linking this to Science Sunday at Adventures in Mommydom.