The sentence "You are walking to school" is perceived as a non repetitive activity happening now (teraz "idziesz"), therefore the verb referring to the repetitive activity "chodzić" (to go, to attend) or "chodzić na piechotę" (to go
on foot = to walk) seems to be more appropriate for this translation:
Chodzisz do szkoły - You go to school/You are going to school/You attend
school/ You walk to school (Zwykle chodzisz do szkoły na piechotę/pieszo)
Because after 'do' it's a genitive. Where do you go? To school - do szkoły.
Look here for a basic oversight of prepositions and their cases: https://en.m.wikibooks.org/wiki/Polish/Prepositions_as_hints_to_declensions
In general, the course has a problem with understanding and teaching the progressive aspect of the verb. The good news is that thanks to persistence
of some native English speakers the sentence "You are going to school", the equivalent of "You attend school" and "You go to school", is accepted as the translation of Polish sentence "Chodzisz do szkoły".
For one example i can say i am going /walking to school and then the next it's incorrect. Why use the example of "school" as it is habitual rather than a one-off? Genuinely getting so irritated by not knowing what I'm supposed to say when the suggestions are wrong?!??!?!