Best Pre-made Educational Content Resources

When I was a classroom teacher, I recall many anxious afternoons and evenings spent scrambling to come up with quality content for a lesson I had to do the next day. Even when I was planning further ahead, it was a stressful, excruciating process to line up resources that I could use for various topics and standards. Now, more than ever before, an abundance of free resources exist that we can conveniently use the next day. In fact, so much exists that it is difficult to sift through it all. Here is a list of sites that I have found to offer quality materials. I wish I knew of them when I was teaching.

• Mastery Connect (Link)- All resources linked directly to common core standards (still relatively new so many standards are not populated, but they offer prizes to those who contribute)
• CK12 (Link) 
• Sophia (Link) 
• Nettrekker (Link to MILearnport account creation site) 
• MI educators can create a free account here and then go to the Nettrekker link from the main page.
• Hippo Campus (Link)
• Khan Academy (Link)
• Math Train TV (Link) 
• Explore Learning Gizmos (5 minute free trial per computer, per Gizmo, per day) (Link)  

That's the list. Happy hunting, and if you know of others, please add links in a comment.