Bobo made the blue water by squirting his ketchup bottles of blue food coloring diluted with warm water into the bubble bath. He made clouds with shaving cream. You can't really tell by the photo, but the water is a beautiful turquoise.
A great book to go along with this simple sensory tub is It Looked Like Spilt Milk. I love sharing this story with a big group of children, because you gets lots of different answers as to what each picture looks like. Share this story with your little one, then ask what shapes your shaving cream clouds look like. You may be surprised by his/her creativity!