In both ms and hs I have started with contour drawing. I ofen bring in
donuts or cookies and have the students so four versions of the donut from
whole to a small piece. They can eat the donut as they work on smaller
pieces (if they want, and not all the students will want to). This forces
the class to look at the food as it changes. Another lesson I often do is
empty my junk drawer at home with one object apiece in brown paper lunch
bags. The students cannot look into the bag. They have to feel the object
and they are all common objects and draw what they feel. These drawings
almost always come out great. The bags get passed around the class so
everyone does 3 or 4 during a period.
I progress from contour drawings to shaded drawings to color.