I'm surprised no one has mentioned Soulver yet (https://soulver.app/). I have used it for years -- it looks like it has pretty similar functionality to this but (IMO) with a more native-feeling UI. I love it.
I don't think it supports as wide a range of math, but it does seem to pass the accuracy test given in the article (sin(exp(37))). It also lets you assign variables which I find handy.
On the other hand, the propagation of uncertainty in Chalk is very cool.
Misleading graphs: in the results section, figure 1, the y-axis for the first graph ("Score of reading test") starts at 6, which makes it look like the paper medium has double the comprehension score of the smartphone medium -- actually it's only about 9 vs 7.5. A difference for sure, but not nearly as big as it visually appears.
That is a kind offer and probably a good way to go, but I have a small objection: I think at the end of it, OP would be a zellyn-taught software engineer, not a self-taught software engineer.
I don't think it supports as wide a range of math, but it does seem to pass the accuracy test given in the article (sin(exp(37))). It also lets you assign variables which I find handy.
On the other hand, the propagation of uncertainty in Chalk is very cool.