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Raw Milk Separation

Milk is collected from cows and, after a while, the milk forms two different layers. They look somewhat similar but, when poured out, the layer on top is thicker than the layer below. The thicker layer on top is cream, which is made up of fat. Since fat has a higher density than skimmed milk, it separates and floats above the rest of the milk which is more water-like. If you were to shake the milk container, the two substances would combine again.

Location: Stacyville, Iowa Time: Tuesday, February 13, 2024 at 8:30 pm

Driving Question

Why are there two different layers (or substances) in the container of milk?

Probing Questions

  • What do you notice about the substances in the milk container?
  • Do you think there are any differences between the substances?
  • What do you think would happen if we shook the milk container?

Classroom Activities

Students could:

  • Do another experiment based on how and why oil floats on top of water when they are mixed together. This will help students understand what is happening with the milk and could be an alternative if the teacher cannot find non-pasteurized or non-homogenized raw milk.
  • Research milk and what it is made up of.
  • Record observations of the milk before and after shaking up the milk container.


Iowa Core Alignment


Make observations and measurements to identify materials based on their properties

Credit Info

Submitted by Noah Michels.

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