Middle School students are engaged in drawing exercises at the beginning of each class. Though most of these exercises are 10 minute silent focused observation work done solo in the student's sketch book, drawing can also become a boisterous group activity that cultivates the students interpretive skills in both drawing and analyzing quick sketches of their peers.
Observation and realistic drawing can be a tricky skill, because it relies mostly on the drawer's ability to slow down and actually SEE the object through careful looking, rather than the actual physical motions of drawing an object.
Here's a fun website for exercising your "Seeing" skills when drawing, http://emptyeasel.com/2008/07/01/learning-to-draw-the-one-drawing-skill-every-beginning-artist-needs/