California Department of Education Curriculum Frameworks & Instructional Resources (CFIR)
“Curriculum frameworks are the blueprints for implementing the content standards adopted by the California State Board of Education.” This site will tell you what to teach.
Discovery Education Lesson Plans Library
“Find hundreds of original lesson plans, all written by teachers for teachers.” Organized by subject, grade, or both.
PBS Teachers Featured Classroom Resources
From the Public Broadcasting Service, includes 3,500 lesson plans and other curriculum materials organized by subject and then by grade level.
National Teacher Training Institute (NTTI) Lesson Plan Database
EdTechTeacher.org Best of History Web Sites For K-12, includes lesson plans.
Kahn Academy "...over 2,700 videos covering everything from arithmetic to physics, finance, and history...".
Awesome Library
The Awesome Library is a large collection of selected educational materials organized by broad academic discipline (social science, mathematics, etc.), by type of resource (lesson plans, special education, etc.), and by user (students, teachers, counselors, etc.).
ArtsConnected; Tools for Teaching the Arts