Drag a rock to the category you believe it belongs to.  If correct, yay!  If incorrect, boo!  Make sure to drag the rock back to its starting position before you move it or another rock to the next box :)

Drag and Drop Rocks by Jenny Hoffman is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
This software incorporates JQuery Google API.