Oh my goodness, I can’t believe that we did this milk and dish soap science experiment so long ago and haven’t shared it with you yet!
Basically, we found this really cool science experiment that is quick to set up, uses household ingredients you already own, is easy to clean up, and is attractive to children who are bored by science yet excited by art.
I decided to set it up as a Montessori tray, knowing that Ella would likely select it first thing (so the milk wouldn’t be left sitting out) but you could always put a note on the tray that the teacher/parent has an additional component. (We use green sticky notes for this signal.)
This post is going to be a bit picture-heavy, but I think you’ll agree that the pictures help tell the story of this experiment.
We used our child-sized glass pitchers to pour some 3% fat milk into a clear bowl (to better see the effects).
Ella carefully and methodically added a few drops of food colouring to the milk.
And then, ever so gently…
Added one drop of regular old dish soap.
What you see here is the dye racing away from the point where the soap was added, which broke the surface tension and weakened the fat and protein bonds naturally found in milk.
The soap is seeking to attach itself to the fat molecules, which is how soap cleans — it bonds to other molecules and then is attracted to water, pulling the attached molecules away from the dirty hands or plate that it was on before washing.
This science activity makes a great compliment to a hygiene or self-care study.
After the initial experiment is over, you can swirl the colours back into the milk and use it to paint! You can even repeat the experiment on your paintings (these paintings are a bit too soggy to last unless you use a heavy canvas or wooden surface).
What do you think? Would your kids enjoy this milk and dish soap science experiment?
And… I would hope it goes without saying… but don’t let the kids drink the milk after this experiment, or you may have an Alfaalfa bubbles situation on your hands…
Do you have a little scientist who would love this colourful science experiment?