The Key to curriculum is a supplemental resource to introduce or reinforce concepts from Fractions through Geometry. Each topic is comprised of a set of booklets that can be purchased as a set or as individual books. The Measurement set has four booklets. There is also an answer key and reproducible tests available separately for most sets.

Students using Key to Measurement enjoy a variety of hands-on experiences related to the English system of measurement. Group projects are included in addition to numerous individual activities.

Book 1 teaches students how a linear measurement system is developed and then presents interesting and fun activities related to measuring length.
Book 2 focuses on length, perimeter, and area measures.
Book 3 develops the concept of area and introduces students to volume.
Book 4 covers a variety of topics with students weighing objects, measuring capacity, and learning about temperature and time.