Egg carton, eye dropper, water and assorted small found objects that either do or do not absorb water (such as buttons, cotton balls, fabric, sponges, paper towel, napkin, toilet paper, etc)
You might show your child how a towel absorbs water. Have your child put the found objects in the compartments of the egg carton. Using the eye dropper your child will add a few drops of water on each item. After discovering which items absorb water, 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.