Erica Kepler

When life gives them a problem to solve, Peg and Cat make lemonade -- and get a lesson in bartering -- in a refreshing new math adventure. It's a hot day, so what could be cooler than setting up a lemonade stand? When Peg needs some marbles to keep her special marble company, she and Cat decide to sell lemonade in exchange for ten marbles a cup. But the Teens have other ideas. "But just one cup for ten marbles?" says Mora. "I'm not made of marbles!"...