This is a really important drawing assignment that I cover in grade 12 visual arts.
(In grade 11 we do fabric drawings to lead them up to this assignment).
We're lucky enough to have a full-body skeleton in science, that they loan to us, but if you don't have that, students can always work from printed/projected images.
It's a three part assignment to get them working on their observational skills, proportions, value, and of course there's a creative component to it as well (students LOVE this part of the project the most!).
This handout goes through
-The 3 parts of the project (whole or half a skeleton / single body part / creative final drawing)
-Student exemplars of both
-A proportions of the skeleton handout (to use as a reference)
-A rubric to make marking easy
It's a flexible assignment in that you can cut it down to just do ONE part of it / use whatever materials you wish - it can easily be tweaked to fit your class needs and your time allotment for the drawing unit.
We use this as an important part of their final portfolio for post-secondary applications.
Hope it helps!