Consider a still life that can be set on a student's table ..hot glue still
life pieces to a cardboard base. Students can keep track of how it was
positioned on their table from day to day. That way they can all see it and
yet each has a different view.
As far as backpacks are concerned. ..in my crowded classroom, backpacks must
go on counters, or under a table so I can walk around.
You did not say if you teach strictly Painting or a more general art course.