What you can talk about:
- Milk is a mixture of water and tiny bits of fat. Fat is lighter than water, so fat floats to the top of a container of milk. There it can be skimmed off and collected as cream. Like regular milk, cream is also made up of water and tiny bits of fat, but the ratio of fat to water is much higher in cream than it is in milk. Discuss with your child ways people use and eat cream, such as whipped cream, cream in coffee, sour cream, cream sauces, and ice cream.
- The tiny bits of fat in cream or milk are like small balloons full of butter. When you let cream warm to room temperature, hard crystals form inside the balloons of fat. Once you shake or mix the cream, the crystals cut and burst the “skins” of the balloons of fat and let the fat out. The fat then clumps together, eventually forming large lumps of butter. In addition, the warmth lets special bacteria grow. These bacteria produce acids that keep other, bad bacteria from growing. They also give butter a good flavor.
Image Source: Phil Brown