Less Than Zero is a book in a series of books by Murphy relating mathematical concepts in story form. This particular book has the following succinct summary on the back cover:
Perry the Penguin needs 9 clams to
buy an ice scooter—but he’s not very good at saving. As Perry earns, spends,
finds, loses, and borrows clams, a simple line graph demonstrates the concept
of negative numbers.
To add to the summary, Perry has ‘less than zero’ clams for a part of
the story because he borrows clams to buy things besides his ice scooter. In
the end, Perry gets enough clams to buy his ice scooter by getting a loan of 4
clams from a neighbor that he will pay off by working shoveling snow, so he
ends the story with a debt of negative 4 clams/hours of work.This book has two possible messages to talk about with students. One message is about negative numbers and what negative numbers mean when applied to amounts of money. The other message is telling students that if they borrow more money than they have, then they will be negative in how much money they have. Furthermore, the second message also puts being negative money as something unfavorable and should be avoided.
Although I read it with middle school students, it could be used with almost any age to introduce negative number concepts, graphing practice, or just as a story about saving money. My students thoroughly enjoyed it, and I hope you find a use for it with your students.