Check out these classroom supplements!
CK-12 - geared toward grades 6-12, this is a site that allows an educator to create their own textbook or just use the wealth of resources as needed.
MIT Blossoms- Math and Science video lessons designed for the high school classroom.
Curriki- a wealth of classroom resources from many different subject areas.
UH Digital History- This site includes curriculum relevant material for United States History from the First Americans to the 21st Century.
Federal Registry for Educational Excellence (although not a textbook replacement, this site is a true registry of thousands of digital resources broken down by subject and grade level).
National Geographic: A great resource for ALL subjects, not just Science and Geography. Includes ideas, activities, interactive lessons and more. Filter by grade level.
Common Sense Media: A resource that provides information and lessons that aid in the instruction of digital citizenship and digital literacy.
Graphite: A site dedicated to helping you find the right tools and sites for your curriculum. Includes reviews and ratings as well as top picks by category/subject/grade level. I would say this is a must have resource for teachers (this is a feature within Common Sense Media).
Digitalbytes- Teach digital citizenship to your students through their own ACTIVE participation in the process (another feature sponsored by Common Sense Media).
LearnItIn5.com A resource to teach teachers Web 2.0 strategies in 5 minutes of video or less. Many categories to choose from.
Teaching Channel: A site dedicated to educational videos that highlight teachers and their innovative and effective teaching methods. The site is organized by subject matter.
NRICH: A site dedicated to mathematical critical thinking skills. All levels of math problems are available. The math problems on this site will definitely get your kids thinking.
Open Ed: A catalog of free educational resources for K-12 including videos, games, assessments, and more. Teachers can create their own "course" and store favorite resources to share with students.
Pixabay- an abundance of public domain images to be used without worrying about copyright infringement.
ReadWorks- site designed to improve students' reading comprehension
EdShelf- A site to help you search/discover educational tools for your classroom.
Edcite- create your own online content and share it with your classes.
DogoNews - Created by National Geographic, one of this site's great features is the News tab. Students (K-8) can read news articles and then answer comprehension and extension questions dealing with the article.
Brainden- This is a fun site full of puzzles: paradoxes, logic puzzles, riddles, and more.