Background: I teach sketching and drawings skills in two of my courses, IAT 208: Drawing as Inquiry, IAT 106: Spatial Thinking, and IAT 336: Materials in Design. Both are introductory lower-division courses.
In terms of challenges, the students had three challenges: (1) Perspective Projection. To draw a vehicle using the principles of two-point perspective projection. Students found it easier to draw a bounding box in two-point perspective before drawing the vehicle. (2) Draw Ellipses (for wheels). The greatest challenge for students was to draw the wheels in perspective. I taught the traditional technique to draw an ellipse using a square in perspective and segmented circle, but students found this difficult to draw. My students were much more receptive to using my plastic ellipse guides. (3) Line Weights. Another challenge was for students to modulate line weights. particularly employing a heavier outline and lighter linework for details. (4) Marker Rendering: The main challenge that students had with this exercise was picking up marker rendering techniques in a relatively short period. As this was a comprehensive introductory drawing course, only one studio lab could be dedicated to teaching this skillset. Accordingly, a majority of the lab time focused on practicing the the application of clean, parallel strokes and overlaying. Students also had to think about the realistic application of light and shadow to make the rendering look realistic.
Above: For this 3/4 view sketch of a concept car (IAT 208), the student built upon the skills learned in perspective projection and rapid visualization lectures (e.g. hatching and varying line weights. Thebiggest challenge was creating convincing ellipses for the wheels.
Above: Task: For the llustration of the hair dryer, students laid down parallel strokes and adding overlayed marker strokes to create a gradient. Additionally, students added 'farkling' or pin-point highlights using goauche or white liquid paper applied with a brush.