The Living Environment class at CHS just finished up a unit on biological molecules this September. The four main molecules they studied were lipids (fats), carbohydrates, proteins, and nucleic acids. To follow up this unit, the class conducted a "Magic Milk Lab,” in which they experimented with lipids using everyday items like milk, dish soap, and food coloring.
Students set up plates with a thin layer of whole milk on them and added drops of food coloring to the milk. They then inserted a cotton swab with a little dish soap on the tip into the milk and, to their amazement, they witnessed an "explosion" of color in the milk!
The next step was to try the experiment with different liquids (skim milk, half & half, and water) along with different types of soap and compare the results.
“This lab is a ton of fun and has aesthetically pleasing results,” explained CHS science teacher Brooke Kneller, who added that the goal of the experiment was for her class to answer the question, ’why does this happen?’
“The answer is that fat molecules don’t dissolve in water. When soap is added, it breaks up the fat cells and allows them to attach to water. The water portion of the milk then carries fat away from the soap. The food coloring molecules are bumped around by the escaping fat molecules and Boom! Color explosion!”