30 Days of Science - Day 7

These are water absorbing polymers or "jelly marbles".  They start off small and solid about a quarter size of a pea, then you put them in water and they absorb the water and grow into a much bigger size.   

Fun experiments:

There are lots of things you can do with these.  My very favorite thing to do with these is make them vanish in water.  If you don't add any extra color to them like the cup on the right, you can put the fully grown jelly marbles in a glass bowl and add water to make them vanish!  The neat thing is, they don't really vanish, they just appear to be invisible.  It's pretty interesting.  Read how to do the hidden message trick with these on the Steve Splanger website.   

Where to buy:

You can buy them at SteveSpangler.com or at Hobby lobby and other places in kits that look like this.  Recently I saw them in the dollar store.  They weren't sold as a science project.  They were being sold fully grown, as a flower vase filler.  Once you use them, you can let the water evaporate and keep them again for another time. 

Conserving water in the environment:

These "jelly marbles" are an example of a hydrogel.  Hydrogels are used in gardening as a way to conserve water.  Imagine areas in the world with little water, being able to use these in their gardens to conserve water, and release it to plant roots when needed.  Amazing.  My grandpa Park used to travel to 3rd world countries and teach them how to farm.  I doubt he ever knew about this though.  I'll have to ask him.  As always, Steve Spangler can teach you more.