Simply touch the interactive pen to a Hot Dot and the Talking Hot Dots® Pen (pen sold separately) responds instantly with a green light and positive sounds. Incorrect answers receive a red light and a gentle wrong sound or phrase. This set of 36 colourfully illustrated cards provides 72 early learning activities in a handy storage carry case. Recommended for Ages 3 - 7 Talking Hot Dots Pen Sold Separately.