This is the best resource available for online classes. You can learn math, science, art, computer science, and more at your grade level.
A bunch of projects from Scholastic - you can also choose your own grade-level here.
Watch some educational videos from PBS.
Play a game while maybe learning some math along the way.
NASA-curated activities, videos, and the like.
Play games and learn about NASA.
From the Natural History Museum of Utah, you can attend live science classes.
You'll need a parent to sign up, but then you get great educational resources.
Lots of super interesting educational videos with illutrations. My favorite is The Bug that Poops Candy.