This is a website made by the Ohio State University history department. It contains some primary sources and maps, a lot is about US history and its wars. One of the coolest things is the timelines that are pretty comprehensive.

This is a helpful cite for world history teachers specifically. It has some sample lessons as well as some additional resources for how to teach a world history class and help make it interesting.

This cite has complete lesson plans for various grades and subjects, but I think that Social Studies and Science will find it most helpful. There are also activities that the students can do at home or during class.

This is a good site for teachers to check in on and learn new things to teach. Also, it could be used to have the kids read an article and reflect on it or use for research.

This site has several different activities that correlate to different textbooks. I found that the activities are still quite good even for a different textbook than the one in your class.