Haha, wow that is amazing! How are you liking the class so far? Thank you for the kind words, but unfortunately I have never drawn denim before. If I were to try though, I would probably draw with the pastel on its side to get a textured effect, then blend it out only a little. Then I might try to lightly draw some of the diagonal parallel lines with a sharp point like a colored pencil or something to give the general idea of the "denim texture". Might want to practice on scratch paper first in case it doesn't work out. Hope this helps!
-Olivia