@Griffin If the assignment is composition and value try to find drawings "coloured in" not just line-based. I think if you find some really nice compositions in line work then use them for the composition part only. I suppose once you find work whether paintings or drawings and do the value study part, you could try and place what you learn value wise to the line drawing compositions to experiment. If you don't want to do that much work I'd stick to the homework more closely. I am sure you could find other line based work that has more values -graphic novels etc.
I very much enjoyed this class though I never completed it and struggled to apply it to my own work. I look forward to returning to it in the future.