Each read-aloud book in the Mouse Math series focuses on a single, basic math concept and features adorable mice, Albert and Wanda, who live in a People House. Entertaining fiction stories capture kids' imaginations as the mice learn about numbers, shapes, sizes and more. Over 3 million copies sold worldwide! Albert is going to the Mouse County Fair! But when his best friend, Leo, isn't home, Albert decides to have fun for both of them. Double the fun!Every Mouse Math title includes back matter activities that support and extend reading comprehension and math skills, plus free online activities. (Math concept- Adding doubles).