I love radial balance. Here's a watercolor version our 7th grade just got done with. I think they each turned out so unique.
I had student design their pie shape, and use graphite on the back of the pattern to transfer the image. They then outlined with oil pastel to separate the sections.
We have a lot of WONDERFUL examples on my flickr site. Please click here.
Click here for previous post of other radial balance projects. (7th grade radial balance, more on radial balance, and elementary radial balance)