Our magic marbles grow right before your eyes—just add water! Simply place the dehydrated marbles in a large tub...fill the tub with water...and watch the marbles become bigger and bigger. The more water you add, the bigger they grow! Then invite children to reach their hands into the marbles—for a unique sensory experience they won’t be able to resist. Best of all, the marbles can be used again and again—simply dry them out to return them to their original size!