We used a lot of websites for classes (And I mean including all the subjects) and some are yet similar, same webiste, but we just use it for different purposes, I think the page I like the most that in basically all my classes we use it BrainPop, it's a website where they show educational videos to children about a certain topic, like it shows videos for science, math, history, and Language Arts. This site is used for mostly all of the classes, they show many detail in their videos and get students learning without even knowing it! It's very helpful and very quick too! 

I mostly like to use it when we have assignments and I want to know something that I forgot, so to do so I watch the videos and re-learn it, it was a helpful site for me!