Through the medium of word problems, these books are designed to help teachers and students develop and employ operation sense, meaning to understand the meaning of multiplication and division, in the context of solving problems in a coherent way. The books support teachers in scaffolding the use of word problems and provides practical examples for introducing students to verbal, contextual, concrete, visual, and symbolic representations, helping students make sense of the operations (both conceptually and algorithmically) across elementary and middle grades mathematics.