This is a perfect end of the year lesson as it involves minimal materials, keeps all students engaged and has pretty great results for all kids. I did this lesson with Grade 6 and it took 2 - 40 minute periods to complete.
You'll need: heavy white paper, thin washi tape (I bought mine at Michaels)
and watercolour paints (we use Prang).
Students simply use the thin rolls of washi tape to create a geometric design on their paper. They can also put masking tape around the edges to create a white border which looks really nice.
Then, using watercolours, they paint all the different sections. My students have alot of experience with watercolours (it's my favorite medium!) and know colour theory pretty well so I saw alot of them stuck with analagous colours and most used the wet-on-wet technique. But I pretty much let them do whatever they wanted.
Let these dry overnight and then the next class the kids get the oh so
satisfying task of peeling of the tape!
Some Grade 6 results: