Ak first discovered these water beads.  She had used them in her classroom before and recently spotted them in stores.  Please see her original post on them.  
A water bead is a water-retaining polymer.  You can learn more about them here.  www.waterbeads.net  I decided to do a search on Polymers instead of water beads and had a much better result.  For those of you still having a hard time finding them, I think that would be a better search for you.  
Not only are these fun to play with just on their own but we’ve been having a TON of fun with them on the light box.  :-)  

RL  

Wow!
Put them on a light table for a whole new perspective!
After doing a search on Polymers I found these “Block polymers” from no other than my favorite store…. Discount School Supply.  LOVE them!  I added them to our products we love which you can see here.  
They didn’t quite take block form yet.  We just got them today and I told my daughter she could play with them before she went to bed.  Will update tomorrow after they “grow” a little more.