Electrify math learning with two-sided Hot dots cards and the Hot Dots Power Pen (sold separately). Each card features an equation with possible solutions. Children respond by pressing the Power Pen to a hot or cold answer dot, correct answers are rewarded with lights and sounds, or a Boing for incorrect ones. Can also be used as conventional flash cards without the Hot Dots Power Pen. Each set of 3 1/2 x 5 inch quick-sorting cards is packaged in a sturdy reusable plastic box. 50 cards per set. Facts 0-9.