Investigations in Number, Data, and Space is a complete K-5 mathematics curriculum that has been designed to help all children understand fundamental ideas of number and operations, geometry, data, measurement and early algebra. Investigations utilizes a research-based, child-centered approach to teaching mathematics through engaging activities, discussions, and problem solving. Students are involved in meaningful mathematical problems, and teachers engage in ongoing learning about mathematics content and how children learn mathematics. Supported during its development by the National Science Foundation, one link is to the publisher's website and another is to the project site.