The basic concept behind perspective is learning that the further away objects are, the smaller they appear. This painting idea comes from one of the Usborne art books, all of which I am very fond of.
1. The students need a set of watercolor paints and good brushes (including small thin ones for detail work). They can start by painting an off-center tree, with trunks and branches. Remind them that trees tend to make forks and split off again and again as they grow up.
2. Colored leaves in varying sizes are painted next. Some may be left on the tree, some floating away or even off the page, and a few extra large ones. Some details may be added with the brown paint used for the tree.
3. If you have time, let the tree and leaves dry before proceeding. The grass may be painted next, taking care to go around the leaves.
4. Finally, a sky fills in the background.