I checked really quick to make sure it would eventually wash off, it would, so I let her go.
She was absolutely silent and focused on her work.
After a while, without any words spoken or direction from me, she washed off her drawings and started again.
This time she didn't stop with one side of the tub.
Again, without saying anything, she got up and moved to the end of the tub for more room to draw.
Then she stretched out on the floor to get the bottom of the tub and eventually colored the claw feet of the tub!
I wish I had noted the time, because she was doing this for a LONG time. Washing and starting over again, and washing again, and drawing some more. At some point she told me some part of her masterpiece was mommy and daddy and a space ship. Cool! I got all the laundry folded, switched out summer clothing for fall, organized drawers and Lydia had a BALL!