Try soap, a ping pong ball, a toy action figure, or just about any waterproof object. If your children leave the water running while they brush their teeth, try having them plug the sink before they begin. Ask them to think about how full the sink will be when they are finished. Read counting books out loud, or read books that rhyme, repeat, or have numbers in them. Reading is fun and a special way to introduce mathematics topics to your children.
Some children love to count along with the pages and others love to identify the number.
Look for patterns in their pajamas or let them pick their favorite color. The important thing is to get them thinking about color, shape, size, and relationship.