Book excerpt: Frog friends, Matty and Moe, are off with a "Ready, Set, Hop!" They both made it to the rock, but who's in the lead? If Matty hopped 5 hops and Moe hopped 2 more hops than Matty, then the score is 5 to 7. But then they're off again. Any child who can add or subtract can build a simple equation, and Matty and Moe make it fun. As readers count along with Stuart J. Murphy and Jon Buller they will sharpen their problem solving skills and find out which frog is the better hopper.