The general idea seems decent, and "just slightly above your skill level" is a real learning technique. One thing I'd be careful with is hints. In math you need to struggle through a problem to really get it, and students tend to instantly look the hint up instead. Self-restraint doesn't work here, so I'd think about how the app gates them (couldn't tell how you handle this since I didn't sign up). Some smaller notes…
Appreciate the feedback! From our data, kids don't request for hints unless they need it but it definitely makes sense to have some form of a gate. As for the website, that's an open problem. Was there a specific part that didn't make sense or was too ambiguous?
Took another look to be specific. I think the information is actually all on the page, but it's never said in a plain sentence. The headline gives the outcome ("A grade ahead in math") and the sections give the feeling ("Never boring. Never impossible.", "A quiet starting point"), so I had to piece together the actual workflow myself from the Sketch / Show work on paper / Ask Hope cards. Something like "Hope gives your kid a problem, they work it out on paper or the sketchpad, Hope reads the work and nudges" never appears anywhere, even though after reading the whole page I believe that's what it is. Also the hero replay moves too fast to actually read the exchange, and that demo is the one thing that would show what Hope does.