What is the chemical reaction in a home-made high-bouncer ball?

I took the kids to the Science Museum in Canberra ([Questacon](https://www.questacon.edu.au/)) and one of the toys we brought back was a [Home-Made High Bouncing Ball](http://www.csiroshop.com/high-bounce-ball-kit/). 


Now I did it with the kids and it was amazing. You pour the powder in the mould, hold it underwater for a minute. Dry it in the mould for two minutes and open the mould and let it dry. 


The end result was like the high-bouncer balls we used to play with as kids. (Lots of fun). 


My question is: **What is the chemical reaction in a home-made high-bouncer ball?** (I'd also love a picture I can show my kids - but that is not essential). 




I have google it and got the link which explains the process but don't show the organic reactions(might be because they are complex)



> 
> This activity demonstrates an interesting chemical reaction, primarily between the borax and the glue. The borax acts as a “cross-linker” to the polymer molecules in the glue – basically it creates chains of molecules that stay together when you pick them up. The cornstarch helps to bind the molecules together so that they hold their shape better. - See more at: [Sciencebob](http://www.sciencebob.com/blog/?p=558)
> 
> 
> 


 0