Instructional Materials Center (IMC): K-12 Textbooks (Print and Online)

Elementary/all grades

• ck-12

  Science, math, social studies, digital media, countries - multiple grade level bands

• UnboundEd - math curriculum for grades PK-12

Middle/High School

• Open Up Resources - Math 6-8
• Core Knowledge

  Curriculum for grades K-8. Account required to view and download full ebooks

• Siyavula - science and math textbooks

Elementary/all grades

• Elementary GLOBE - from NASA
• ck-12 

  Science, math, social studies, digital media, countries - multiple grade level bands

Middle School

• Core Knowledge 

  Curriculum for grades K-8. Account required to view and download full ebooks.

• Siyavula science and math textbooks
• Utah's Open Textbook Projects
• HippoCampus - although the site says they are videos, many modules are interactive texts

Elementary

• Michigan Open Book Project - Social Studies - Open textbooks for kindergarten through high school.
• Core Knowledge - Curriculum for grades K-8. Account required to view and download full ebooks.

Middle School

• U.S. History

• Michigan Open Book Project - Social Studies

  Open textbooks for kindergarten through high school.

• Ancient Civilizations

• American Government

• Building Democracy for All: Interactive Explorations of Government and Civic Life

• Core Knowledge 

  Curriculum for grades K-8. Account required to view and download full ebooks.

High Schoool

• Building the American Republic

• The American Yawp

• Ancient Encyclopedia

• American Government