Booklist (October 1, 2011 (Vol. 108, No. 3))
Grades 2-4. Although it’s not unusual for a math book to explain equations and how to solve them, it is unusual when the setting is a haunted house on a moonlit night. First, this picture book introduces the idea that an equation is like a seesaw with one side balancing the other and the notion of a variable, “X,” as a mystery that can be solved. After demonstrating a few equations with easy, guessable solutions, the text begins a narrative about Mandy and Billy, two children who have been in the illustrations from the start. They visit a haunted house, where caretaker Igor (and the household cats, bats, and skeletons) demonstrate how to solve equations using addition, subtraction, multiplication, and division. The story and lessons move along at a steady pace, while the eerie yet cheerful digital pictures illustrate the spooky setting, weirdly appealing characters, and even word problems with verve and style. An equation-related activity rounds out this kid-friendly introduction to basic algebra.