Incase anyone else has the questions I had, this cartridge goes with "The World of Dinosaurs" book for the leap pad reading system. Here is the description from amazon: "Your child will lead the way to learning with these LeapStart Books. The World of Dinosaurs use character voices, sound effects, music and instructional guidance to help kids strengthen their language, creativity, exploration, reasoning and motor skills. In The World of Dinosaurs, your third, fourth, or fifth-grader will go on a science and reading-comprehension adventure in the prehistoric realm. Includes a book, cartridge, which enable audio interactivity. For use with the LeapPad Learning Center (sold separately). Each book sold separately. Recommended for ages 6 to 10." Hope that helps!