First we did some watercolor painting onto a Arche's cold press, 9 x 12 sheet. This is the paper we use for most of our paintings. It's more expensive than student-grade paper but it's sturdier too, which allows Isia to rework and experiment with the surface without it falling apart. It's also thick enough to hold up to lots of water and you can even create a whole new painting on the backside. Isia started with a brush, but ended up using her fingers just as much. She's really fascinated with her fingerprint these days!
Then it was time to introduce her painting to the rain:
Do you see those beautiful interactions between rain and paint on the surface? That's another reason hefty paper is needed for this project, otherwise the paper will soak up water from underneath instead of just pooling on the surface. Then, when it dries...
... you can see beautiful burst patterns where the rain hit the paper. Looking closely, you can also see the imprint of each raindrop too, which makes the paper appear speckled. They're like little white rain "fingerprints" in the paint!
A toddler recommendation: For our little people with short attention spans, you might consider creating your painting in one sitting then stashing it away "for a rainy day."
An older kid recommendation: Older kids can make guesses on what they think will happen when the rain hits the paint. After-wards you can discuss why the rain leaves white dots behind (the force of the rain drop propels all the paint out of that area) and follow-up with other artful experiments like collecting raindrops, here. It would also be fun talk to debate whether or not they think nature is an artist too in their artwork.