When backyard sluggers Brother and Sister join the Bear Country Cub League, they get real uniforms and play on a baseball field. They also have pressure to win and competition from the other cubs. But it's Mama's advice that helps them prepare sensibly for team sports.  

From the Trade Paperback edition.

Annotation

Brother and Sister Bear are such good baseball players that Papa Bear decides they should try out for the Bear Country Cub League.