Freezing Lakes

Lakes tend to freeze from the top down. This is because water’s density is greater than that of ice, so the particles of water that approach the freezing point first float to the top of the water as they freeze. In this phenomena you will learn about how lakes freeze in the winter and what density is. Without having our lakes hitting maximum density, lakes would never freeze in the winter.

Driving Question

• Why do lakes freeze from the top?

Probing Questions

• During November or December, as the air temperature and the water at the lake surface becomes colder than 39 degrees Fahrenheit, what do you think happens to the water?
• Why do you think shallow lakes usually freeze faster before deeper lakes?
• What do you think is more dense, water or ice? Explain why.

Classroom Suggestions

Students could:

• Watch a video that shows how ice is formed.
• Read “Freezing and Melting” by Robin Nelson.
• Work through an activity about how ice forms. 

Relevant Related Resources

• When and How Do Lakes Freeze?: This article also explains why lakes freeze in the winter.
• Lesson: A lesson plan about how water freezes.
• Oil and Ice Density Activity: This activity explains how density works.