Student or Passenger
A student remains a student at all times that a lesson is being conducted from the briefing to the end of the debrief.
The qualification; to be one and not the other is not whether they are actually controlling the flight of the aircraft but whether they are being instructed. During a lesson the student should never be passive. They will be observing throughout. If i was the student and my instructor told me to entertain myself for a few minutes while i do the take off and fly to the training area, "i'll let you know when we are there". Well, i would expect only to pay for the period that i was being taught and not chock to chock. I would also change my instructor or flying school.
Mike your interpretation is perverse and not in accordance with any syllabus of which i am aware.