It is so much fun to be a penguin—especially when you can swirl around on your very own ice scooter. Perry really wants one, but they cost 9 clams and he doesn't have a clam to his name. Then mom pays him 4 clams to trim the ice in front of their house. Perry decides to make a chart to track his savings. So far, so good! But then he goes to the Ice Circus with Fuzzy and it costs 5 clams. Fuzzy lends him the extra clam and now Perry is in debt and has to mark his chart at "-1." When Baldy loans him 2 clams for a Fishy Float, the total dips even further, to "-3." Will Perry be able to climb out of negative number territory, pay back his friends, and make enough money for a scooter? Good thing there's always plenty of snow to shovel!

The introduction of negative numbers extends a child's knowledge of the number system and is an important concept in algebra.

MathStart is an award-winning series by Stuart J. Murphy that teaches math through stories and visual models. Young readers find the stories engaging and relatable, because each story revolves around practical applications of the math concept being presented and features lively art from top-notch illustrators.

Charts and other visual representations help children understand how the math works and promote deeper comprehension. This unique combination of stories, illustrations, and visual models helps teachers and parents in the teaching of math and provides all children with the opportunity to succeed.

The 63-book series is divided into three levels with 21 books in each. The math concepts taught in MathStart books conform to state and national standards. Level 1 is Pre-K–Kindergarten; Level 2 is Grades 1–3; Level 3 is Grades 2–4. The series follows math topics across grades so there is a foundational path to learning that runs through the levels.