My kids will be entering 9th and 11th grades, and I’m trying to make sure they stay busy this summer. Does anyone have suggestions on online courses, particularly those that are STEM focused?
Are you looking for free classes, or are you willing to pay?
Is either child studying a language, or planning to? Duolingo is fun.
The kids could get a head start on an upcoming class they’re anxious about, or they could have fun learning about something they’re interested in.
While free would be better, I am willing to pay. I’m looking more for math and science courses.
Try Khan Academy, EdX, and Coursera.
Check out The Great Courses. Many of these are college-level, but you might find some that the three of you could enjoy together.
The teachers are excellent. One of the calculus lecturers, Michael Starbird, was my calculus professor at University of Texas. He was the best teacher I ever had. He was so good at explaining in class that I barely needed to study for tests.
How interested are your children in STEM? Is that your preferece or theirs as well?
I vote for them to just enjoy summer vacation.
Thanks everyone! STEM is my preference, but I am open-minded with them. And they will definitely enjoy their summer. I’m only asking for 1 hour per day of educational activity and another hour of physical activity.
Consider getting a boring high school class out of the way over the summer. Things like US History, <yourstate> history, etc, can be quickly completed at a community college and frees up a whole year for a more interesting HS class. Check with your HS to make sure they will take the credits. Kids probably won’t jump at the opportunity, but you can present it as spend 3 months to blow through it over the summer or 9 months to slog through in HS.
Khan is pretty darn good at keeping your kid either fresh on the math they just learned or working ahead on the math.
There are some decent documentaries available on Netflix/Amazon - Ken Burn’s The Civil War can be problematic if you are a Historian, but you can easily get through high school course material on the Civil War from it. Just stay away from Ancient Aliens 
There are also some worthwhile literature adaptations that are streamable. A hell of a lot of Shakespeare (if they have to read Romeo and Juliet next year - which I think is now Common Core - watching it first will put them a mile ahead).
Codeacademy for learning to code
If they have started a foreign language, having them just watch foreign language TV can help them keep their ear in the game. I had my daughter read the first Harry Potter book in Spanish one Summer…her Spanish was ok at that point and she knew the story.
My daughter is taking Algebra 2 through Keystone. They offer it online or correspondence (she’s doing correspondence). So far it has been fairly easy (both registration and submitting tests). Unfortunately it’s not just for fun…she failed math this year so has to take it in order to graduate. But so far we’ve been pleased.