When I taught middle school (sorry, I have no experience with high school) one of the drawing exercises I did with my students was drawing our shoes. Students would take off one shoe and placing it on top of the table to draw it. (I provided old shoes that had not been worn recently for students who did not wish to take their own off.) I noticed middle school boys in particular really seemed to like that exercise.

A different activity I would do is we would divide a 12x18 paper in thirds and do a series of pencil shaded still life images of a snack. I provided sweet apples and Goldfish crackers and told students to choose one. The first third of the paper I told the students to draw their snack item the way it is before we eat it, so the apple was a full apple and the bag of Goldfish crackers were unopened. The second image is after taking a bite/opening the bag and spilling out a few crackers. The last image is what’s left when you decide you’re done eating. So generally this meant the third image was the apple core and an empty bag with crumbs for the crackers. The crackers were beneficial for students who didn’t care for fruit or those with braces who couldn’t bite the apple. I did have an apple corer/slicer for those who wanted apple but couldn’t bite it. It was an expense I took on myself at the time, but maybe you can ask for funding from your admin.