Moritz is watching his little brother play in a mud puddle. Moritz notices that when his brother stirs it with a stick, after a few moments the dirt settles back to the bottom of the puddle. His brother is creating a .

Anjali knows that whole milk has more fat than skim milk. However, the solid fat doesn’t seem to separate from the liquid milk even after it has been in the fridge for a few days. This is evidence that m