Pour half a cup of whole milk into two large dinner plates. Add several drops of food coloring to each plate, according to personal preference for colors. Allow the second grade students to experiment with touching the milk with a clean cotton swab near the location of the food dye. Dip a cotton swab in dishwasher detergent and dab into the milk on the second plate. Swirl the food dye with the soapy cotton swab for a fun visual effect. The color swirling in this experiment occurs because of the attraction between the fat molecules of the milk and the soap.
Lead second grade students in separating milk into solid and liquid components through a vinegar experiment. Mix four teaspoons of white vinegar with 1 1/2 cups skim milk in a microwave-safe bowl. Aid the students in heating the mixture in the microwave for 60 seconds. Allow the mixture to cool before playing with the end results. The curds can be strained from the milk, and molded. The plastic milk experiment offer a hands-on introduction to chemical reactions.
With significant adult assistance, children can make kefir from milk and live cultures. Heat one pint of milk to boiling on a stove, and allow to cool to room temperature undisturbed. Add 1/2 ounce live kefir cultures to the milk and mix thoroughly. Place the mixture in a lidded container for 24 hours. The resulting thick, sour mixture is the result of the fermentation from the live cultures. Aid the students in making smoothies from the kefir.
Provide a powerful lesson in the importance of good nutrition by demonstrating the comparative properties of milk and soda. Pour one cup each of milk and cola into large cups. Place a clean eggshell into each container. Aid the students in examining the eggshells once daily over the course of one to two weeks. As students see the effect of the soda's acid content on the egg shells, discuss the similar properties between eggshells and human bones and teeth.