Online learning for 7th graders

My grandson lives with us and is in 7th grade. He is in a special school for hyperactive kids. He is online with his school teachers a couple of times a week and they give homework and ask questions.
Problem is alot of his work they give him he finishes in 1/2 the time they give him so he has alot of dead time, were I have him read.
I have found ALOT of free online math and science stuff for him but was wondering if there was more. Like English and world or US history I could have him do. Has to be free tho my work is shutdown so monies tight. This has always been a life saver for my entire family.

It might not hurt to ask his school if they use Lexia learning or IXL. Lexia is good for English and grammar, IXL is more of an all encompassing learning site.