Your district sounds like ours. When I find a sub that can actually
handle teaching art, I try to book him/her as soon as I know I'm going to
be gone. It's sooo-oooo nice to be able to leave and know that someone
other than the students are in charge!
My funnest plan is for each student to take an ice cream cone and use it
in a surrealistic drawing. They may transform it into something new,
place it in an unusual setting, or have it contain something other than
ice cream. I show them some of Magritte's work and explain the
assignment the day before, and they really get into it.
Another one I do is wire sculptures. They have one class period (85
minutes) to shape a 3' piece of wire. The pieces are pre-cut by me in
advance. They may add colored wire or heavier wire as needed, but they
must cut it themselves.
If they've had linear perspective drawing, they enjoy doing small posters
of their names, initials, or team names in perspective, then coloring
them with markers.