[meaubry]

Karen and Elgin have provided awesome advise. I have taught Drafting at a local college for a number of years. Unfortunately, they dropped the mechanical drafting requirement and replaced it with Computer Aided Drafting. I started my professional life as a board draftsman for Fisher Body. Later, I was one of the early CAD designers. I am a big believer in understanding the principles of 2 dimensional drawing, before creating Math Models. Your observation that "some students don't seem to get it" is normal. Students "get it" at different paces - unfortunately some never do "get it", as they don't have the ability to transform the 3 dimensional object into a 2 dimensional picture. My experience and advice aligns with both Karen and Elgin. Make sure that you really stress the principles - even though there are alot more glamorous topics that could be covered. If you do want to make it a bit more interesting, have the students draw a real world object - my favorite is a Table Top Vice. Just make sure that the objects being drawn are based on simple geometric shapes - then work up to the more complex. Good Luck in teaching this important lost art.