I've never seen "activity" on a form. What sort of form are we talking about?
I have seen "activities", ie hobbies, pastimes. If you write 'student' in both the 'occupation' and 'activity' field, you might appear to be a boring person.
Under "current activity", I would write "filling out a form"! Could you elaborate a bit more? What is the form for?
Student or Learner