In addition to teaching them to draw from observation, you could teach them
how to use drawing and pattern-building to fill a space in a
beautiful/interesting way. Zentangles are a drawing activity that helps to
build confidence and promote relaxation. Anyone can learn to create
beautiful Zentangles...just google it, and you will find a plethora of
information. Zentangles to NOT take the place of the traditional drawing
curriculum, but perhaps you would find the Zentangle concept to be a good
supplement.
I'd be interested in hearing what others in our group think of
Zentangles...I have not used them in my teaching yet, but I think I will
next year. (I teach elementary.)