Here’s a good exercise for basic sketching from Wetcanvas.com, Drawing & Sketching, Basic 101: Class 1. In this exercise, the student draws something using whatever method he/she enjoys. I chose to draw my hand and I did just a quick 15 minute sketch:
Then, the student draws lines and draws circles using only lines. (I did this but am choosing not to post here). Then the student draws the same initial drawing using only lines to made the drawing. I once again drew my hand and here it is:
If you wish to check out this and other lessons (which I highly recommend), here is a link: