I love this art activity I've just finished with 4 of my junior classes (2 year 1 classes, a yr 1/2 and a year 2/3)
The kids all worked in small groups to paint the background of two large canvases. Then I gave them some small pieces (About 20cm by 15cm) on which they drew and painted butterflies or imaginary flowers using acrylic paint. I cut them out and then we arranged them and I used PVA to glue them in place (trying to rearrange them as little as possible- but you know how I am with random sometimes its just too unbalanced!)
The principal wants more of these! They look great in the office.
So I have a plan for some beach scenes next.