As the last week of school is coming to a close, I have a few classes who are ahead of others due to snow days, convocations, field trips, etc. To get everyone on the same page, the classes that are ahead are doing quick one-day projects. This is a lesson plan initially intended as a sub lesson, that is best with 4th grade but works with other grades as well. It's pretty basic, and engages the students for most of the class period, and most of them really enjoy doing it, which is why it's a good sub lesson. It's also one of those projects that if a student does finish early, you can say, "make another one with different colors and/or shapes", and if a student doesn't get it done in time, you can say, "I'm sure you have markers in your classroom or at home that you can use to finish it later."
The only necessary materials for this lesson are markers and paper. Crayons work to, but the students rarely do as nice of a job in crayon. The idea is simple: draw the outline of a small shape 5 or 6 or 7 times randomly around your paper. Then, outline the shapes with another color. The students can use as many colors as they want, and they can do a pattern or make it random. Keep outlining the shapes until they get so big that the outlines touch each other. Then, next time you draw a line, make it go around all of the ones that are touching. Don't stop until all of your lines go to the edge of the page!
I always do a star for my example, and I have taught my students a trick to draw a perfect star. First, you use your pencil to draw a normal criss-cross star (the kind that has a pentagon in the middle). Then you trace over just the very outside edges with a marker, and erase the pencil marks.
Here are a few examples of students working: