Set out at least 2 tubs of plain water. After discussing and comparing, add some kind of soap to one of them (dish soap, bar soap, shampoo, etc.) Submerge, wash, mix etc some various items in both tubs, and observe any changes, differences and similarities. Some items to use might be dolls, doll’s clothes, sponges, a very dirty item, whisk, eggbeater, sieve, and vegetable oil.
What do you think will happen in the plain water? In the soapy water? Did it happen? I wonder why/why not?
Compare and discuss different kinds of soaps – consistency, shape, bubbles, color etc. Try some of each in a container of water, and observe the results. Similar reactions?
Have a discussion about a world without soap – what would it look like? What would we look like? Hospitals, illnesses, keeping safe. Could we use anything else to keep things clean? If possible, try the suggestions.
Extension - when we put soap in the water, some of it dissolved. Try another substance in the water and observe what happens. Examples - sugar, dirt, oil, pebble, lego, tissue.