Whenever possible our instructors utilize demonstrations for educational purposes. Here's something I created for a group at the last session of Character Design I for adults. I used blue pencil for the initial construction and layout, red pencil to commit to the design, black pen for the final pass and blue pencil again for tone. Clicking on the image will give you a better view.
This quick sketch served to illustrate the process of developing a character in the classic animated style, with a full explanation of depth of field suitable for 3D modeling if needed. I judge the effectiveness of a demonstration by the difference it makes with our student's approach to their own work. If I see an immediate improvement, then I know that the demo has done was it was intended to do. With that criteria in mind, this little demo was a success.