great suggestions. sadly i am limited by time and bandwidth. this was a weekend hack that i did by myself, so it's unclear how much more rigorous i can make the analysis. i'll try to incorporate some lightweight edits for clarification, though.
How prevalent is the REPL in CS education?
Does perceptualization play a role?
ideally you want to mix the best of both worlds. here's a prototype demo: https://www.youtube.com/watch?v=Q3oarDuZPL0