This is an incredibly well-executed idea! The art, gameplay, and sound design blend together perfectly. I'm personally a fan of educationally-flavored games, so I was excited to see something like this. And on top of that, the last few puzzles were surprisingly challenging.
From a pure puzzle perspective, I think it's close to perfect. From an exercising math skills perspective, I do worry that when the shapes spell "5-3*4" that becomes "14" instead of what pemdas would say, "-7". Post-jam, it might be worth exploring what about the puzzle design changes if a long string is treated as one pemdas expression instead of two summed expressions.