It doesn't rain very often in Vegas, but when it does I try to take advantage of it! We spent our morning splashing in small mud puddles and digging for worms in our "garden" so it was time to head indoors for a craft.
We colored the paper with washable markers:
Then put them outside to watch the rain distort the drawings. Of course being Vegas the rain wasn't the type I'm used to being from Seattle! I ended up giving them water bottles to help the process along.