my favorite, is to have them do a blind contour of their own hand. i teach
them there is the contour, an outline that involves some detail, which is
modified, then i teach them blind contour. you have them tape their paper to
the desk, turn side ways and look at their hand or an object, hands are good.
they should not look at their paper while drawing. bring in the art history
with degas, he used to go and sketch with a pad in the pocket of his coat
without looking. you get fabulous results.