Egg carton, eye dropper, cup of water, and assorted small objects that either do or do not absorb water (such as buttons, marbles, plastic figurines, rubber or plastic bath toys, cotton balls, fabric, sponges, paper towel, napkin, toilet paper, etc.)
Start by showing your child how a towel absorbs water and explain the concept. Then, have your child put the objects in the compartments of the egg carton. Using the eye dropper, have your child add a few drops of water on each item. After discovering which items absorb water, ask him to group the items accordingly.
Relate this exploration to real life situations. When there is a spill, ask your child what can be used to clean it up.