I was reading a post on another mommy group i'm on and the woman said that her 20 month old could count to 10 but would skip 7. My 19 month old only knows one number: 3.

After calming down from my initial freak out of "OMG my child is so behind" I started thinking of the best ways to introduce letters and numbers to my DD. She obviously has a lot of toys that sing the ABC song to her and she sort of sings the beginning of it but she doesn't associate those sounds with letters.

Does anyone have any great activities, toys, games, books, or apps that they would recommend for introducing toddlers to letters and numbers?