DD, soon to be a 8th grader in California, is looking for online resources to help her get a leg up on 8th grade Language Arts and 9th grade English. Anyone know of good online resources that might help her. Anyone use BYU IS for their English courses?
Read, read, read.
Novels, long form journalist (Vanity Fair, New Yorker), articles in the Economist, Wall Street Journal, Esquire.
It is not only the best way- it will provide her with solid reading and language skills for the rest of her life.
Read, then read some more…and then read.
Just read…read a lot. Read a wide variety of genre…fiction, non-fiction, historical fiction, etc.
The library is your friend…and is free,
Honestly, I can’t see any reason why a student would need to “study” this during the summer to get a leg up. Read…read…and read some more.
If writing is an issue, maybe find a creative writing course…but really…why are you concerned about getting a leg up??
Readers make good writers. Seriously. Read 3-4 classics over the summer and go out for ice cream or coffee to discuss.
What do you mean by a “leg up”? Does she need remedial work because her skills are lacking, or is she shooting for Ivy League and wants to be top of the class- for example? Motives are unclear 
I wouldn’t make reading into a chore with any goal other than enjoyment. Efforts to make kids read seem to backfire in terms of longer term reading habits.
If her skills are good, but she doesn’t like to read, let her do something she does enjoy during the summer as long as it isn’t constant screens.
Does she have a job? What else is she doing this summer?
There are many online courses. If you make the motivation clear, we could recommend some.
It’s summer time. I am sure your local library has grade appropriate reading lists. Visit your local library and have her start reading the books listed.
I would second reading all the time. Also if she’s anything like my kiddo she might need to study grammar. It’s not taught in our school so learning the rules is important ( and boring>
I’m with everyone else I think the best thing an 8th grader can do is get in the habit of reading. It really doesn’t matter what you read - fantasy, sci-fi, mysteries are all fine - you want to become a fast and fluent reader. IMO the best way to learn grammar is to study a foreign language.
For what it’s worth I’ve heard good things about this CTY course - you have to be eligible to take it however - https://cty.jhu.edu/online/courses/arts_humanities/sample_essay_critique_writing.html I’ll say right now, I would never have forced my kid to do this. My older son chose to do CTY courses in mathy subjects because they were fun for him, my younger son went to a traditional sleep-away camp in 8th grade and music camp in 9th grade.
The public library may have a middle school summer reading program. If she is behind talk to her teacher to see what areas are weak and ask for suggestions. If she is on level or above it sounds like she is doing fine. I agree with reading a lot but not making it a chore. My daughter entering 9th grade loves reading and devours books but has no interest in doing her assigned summer reading for school.
Get * The Elements of Style * by William Strunk. It’s by far one of the best books I ever purchased. Helped me a lot with high school English and grammar in general.
As others have said, use the library. It exists for a reason.
She might like to find a different genre too, like poetry or sci fi, if she’s never tried them.
Make a game of summer reading, like reading one book set in every state or a list of books in alphabetical order. If your town has the little book boxes people build in front of their homes, challenge her to find a book (and leave a book) at several in your neighborhood.