Jumping rope is a great cardio activity for kids and adults. It doesn't take a lot of equipment, teaches coordination and is good old fashioned fun. Toddlers and preschoolers can even play by jumping over a rope on the ground or swinging it back and forth.
Include jump rope chants and rhymes to build your child's vocabulary, too. If you don't remember them, click on the link on the left to find your favorite one.
Make sure you join your kids and show them how it's done.