This project turned out to be one of our favorites this last year.  It was very simple for the little ones, but still fun for the older ones as well.

The Idea

Paint a background with watercolor paints.  Use straws to blow watered-down acrylic paint and create a tree shape. Add final details.

The Execution

Supplies:

Watercolor paint
Paper towels (to blot off bits of paint and create cloud shapes)
Thick paper
Acrylic paint
Straws
Paintbrushes

Follow directions from That Artist Woman for How to Paint Spring Trees.  She has a similar tutorial called How to Paint Fall Trees.

The Extension

My kids continue to use this technique to create other projects.