Mathematics Principals Guides were created by New Teacher Center to support strong math instruction in grades 6-8. The principal guides provide content on the "big-ideas", strategies and visual models, key vocabulary terms, and additional resources related to math instruction. They also provide classroom look-fors with specific examples and instructional practices. These guides were intended to increase the integrity and quality of implementation of high quality instructional materials through an improvement in the use of key instructional practices which center students.