I popped 1/4 cup of dishwashing liquid and 1/2 cup of water into my mixer (could use a food processor) and whizzed it up until foam was created. Monnie loved watching the bubbles form! I then transferred the foam into pans, added spoons, small toys, cup cake holders (basically what I had around me in kitchen) for Monnie to play with while exploring the foam.
She even took to finger-painting with it on the dishwasher and then attempted to wipe it clean!
This is a messy play winner as it also makes things clean unless you decide to make it even more fun and add a drop of food colouring!