Put towels or newspaper on the floor so the children will not slip on the wet floor. Mix cornstarch and water together. Let toddlers play with it in a bucket or in bowls with cups and spoons. Make the goop thick or thin. Cut doors and windows in the box to make a playhouse.
Toddlers like to draw with short, fat, unwrapped crayons.
Then have them paste the pieces to make a collage. They like this mess. Put pillows, cushions, or a mattress on the floor. Most toddlers are just learning how to walk and run. Go for lots of walks.