You can find them already hydrated or as tiny little balls (they almost look plastic). Add water and they swell and become a little squishy and a lot of fun!
You can get these in almost any quantity on Ebay (and at a great price)! These water marbles totally capture the kids attention! They are always amazed by how they change once they are placed into the water. While they are expanding in size, they contort into all kinds of weird shapes. We hang up large sheet of white paper and the students write ANY questions they have about the water marbles. We then decide which questions are testable and which ones are not. If you are looking for a detailed water marble science lab packet, click here!