And it is Free! 

Moms and Dads, Friends and Family; I present you with a most wonderful toy. Children have it with them all the time, there are no batteries required, and they can be more amusing than a barrel full of rhinos. "How much does it cost?" you cheer. Well, it costs nothing! "What is it?" you ask. It is, in fact, your children's hands! Hands can be made into puppets, they can clap, and they can turn pages in books. Share this amazing toy with your children today -- hands.

(One of) the Greatest Literacy Tools on the Planet!