Milk, like water, has a property known as surface tension. Surface tension can be thought of as a skin on the surface of the milk. It is created by the molecules in the milk bonding to each other more than the other things around them. Soap breaks apart surface tension. So when soap is added to milk (or water) the strong bonds between the molecules are broken and the milk will start to move around.
Materials
- Small dish or platter
- Milk (2% or whole)
- Food Coloring
- Cotton Swabs
- Liquid Dish Soap
What to do:
- Pour the milk into the dish.
- Add a few drops of food coloring to the middle of the milk. Use all four colors, but make sure not to put the drops on top of each other, they should be beside each other in the middle.
- Dip the end of the cotton swap into the dish soap.
- Gently place the soap covered end of the cotton swab into the middle of the milk and watch what happens.
- As the food coloring moves around you can add more drops of soap to make the pattern and colors swirl and change.
Steppin' Out:
Try this experiment with different kinds of milk or other liquids to see what works. Different liquids have different levels of surface tension (or none at all).
