I make the students at each table share one paint set (4 students per table), which makes things much less messy, with less clean-up. Since they paints I've been leaving with this lesson are "special" glitter paints, the students don't mind sharing! When we use something special, I often have less of it, and the novelty outweighs having to share.
Before my sub arrives, I set the supplies out for her, and hide things that shouldn't be used. I usually put the paints that she needs in a bin on my chair, so they won't be missed. I also borrow all of the library's Rainbow Fish books, and leave them on my chalk ledge.
Here are the instructions I leave with the lesson for my sub:
1. Before class, put the white paper on the supply table.
2. Point out the Rainbow Fish books on the chalk ledge, and ask if any students have read them.
3. Tell the students that today, they will get to create their own rainbow fish.
4. Ask each row, one at a time, to come to the supply table and get a white paper.
5. Once back at their seats, have the students write their name and class code on the back of their paper with a pencil.
6. Have the students look for a black crayon, and hold it up when they find one. (Students who are missing black may borrow one from the bucket on the supply table.)
7. Place picture #1 on the blackboard with magnets, and have the students draw it.
8. Continue with each successive picture, and assist students as necessary.
9. If time allows, color the water blue with a crayon, and paint the fish with glitter paints. Water cups are on the counter by the sink, to the right. Paint brushes are in a cup on the counter. One paint set per table; students will share.
10. At the end of class, art goes on numbered shelves to the left of the window if dry; if wet (i.e. if you had time to paint), on the drying rack on the door to the closet.
Here are some finished pictures created entirely with the sub, from grades K and 1:
Here are the paints the students use: