My high school was super underfunded for art so I only painted on canvas because some guy who lived next to my art teacher died and donated them. Really thankful for that guy, RIP, he was a good guy.
But I have taught some private lessons before (not as an official teacher, but I'm very much trying to either get a job in that field or get a teaching degree to accompany the art degree) and I think what's really important is to draw in the WHY instead of the WHAT when it comes to art techniques. Especially when it comes to stuff like color theory and abstraction vs realism--you have to teach why you use it. Kids are kind of trained to memorize and have a hard time internalizing stuff.
Kinda like how in sports you teach people to play a game, and not just how to kick a ball. I feel like in High School art all I ever did was kick that ball around. It never actually clicked outside the classroom how to combine those skills to make my own pieces.
So anyway, that's what I focus on when I teach. I did a lesson like a week ago for a school nearby and we did it on how to illustrate the night sky (which was HARD over zoom). So I talked about why midnight is perceived as blue although moonlight is not blue. We talked about the science and anatomy of how our eyes work in low light, and the Purkinje shift. (because I think it's helpful to remind kids that there's a lot of science in art. Like a lot of science and needing to predict how humans observe the world--because we often observe things a little off.)
Then we looked at some famous art and I asked em--why does this look like night? Hoping that it would teach em how to approach classic art as a learning tool and not just something to memorize. Kinda like trying to reverse engineer it and ask "why does this work" instead of just being told "see, this works"
Then, afterward, I did a demo of doing washes in watercolor to paint our own take on night skies, since I know they have those paints, and washes are kind of scary to beginners. Plus, washes are kinda quick, and I didn't have too much time to do more than that. But that ended up being a good idea because technical stuff from a professional perspective is very different from an art education perspective, so I was able to explain things in great detail like...how to lift paint when you make a mistake, how to know what brushes to buy and which to use, and how to stretch your paper to prevent buckling. TBH their art teacher was really into the lifting paint thing. They were like "how did you ctrl-z? You can ctrl-z in watercolor???" and that was I think their favorite part.
But I came up with that lesson plan because I was talking to a friend of mine who teaches Drama and she said that she does a lot of "I do" and then "we do" and then "you do" so you want to lecture, then do some discussion or projects with them, and then let them go solo. It was...nearly impossible with zoom in that time limit, but I think they had fun painting, at the least. At least one kid was paying attention, haha.