Using no spacers, the students should be instructed to place washers in the empty cup until the two magnets separate from each other.
(the students; should be instructed; to place washers in the empty cup until the two magnets separate from each other) (the students; to place; washers; in the empty cup)
the students the students
should be instructed to place
to place washers in the empty cup until the two magnets separate from each other
washers in the empty cup