Review excerpt: If you’ve ever tried to bounce a ping pong ball on a paddle, you get the idea of Motion Math — a math drill where you lean your iPhone, iPad or iPod Touch to steer a bouncing ball to the right spot on a number line. After you choose a difficulty level, you see a number line, along with bouncing ball, with a fraction shown on it. If the ball shows 1/2, you try to hit the center of the line, 50% between the 0 and the 1. The ball might alternate between a percent, mini pie-charts or a fraction. If you miss, a set of arrows provides hints, helping you to visually approximate, say, the difference between 1/2 and .65. Subscribers, please log into our database using your password to read the full review along with our rating, and see why this received our Editor’s Choice Award.