Fogged In

Children will learn about fog and how it forms.


Lesson Objective

Children will learn about fog and make fog in a glass jar.


What You'll Need

  • Glass jars – 1 per 2 children
  • Ice cubes – 1 per child
  • Pitcher – 1
  • Small paper plates – 1 per child
  • Hot water (adults do the pouring)

What To Do

Note: This activity works best with small groups. Caution the children not to touch the jars of hot water.

  1. Discuss the weather and clouds with the children.
  2. Explain that clouds come from water vapor, the same thing that causes fog to form (see Did You Know?).
  3. Pour hot water into each jar, filling it up three-quarters of the way.
  4. Have the children carefully place the paper plate on top of the jar, covering the opening completely.
  5. Have the children place their ice cube on top of the paper plate.
  6. The process of the fog forming inside the jar may take a few minutes; discuss what is happening inside the jars as the children are observing (see Guiding Student Inquiry).

Guiding Student Inquiry

  • Tell me about different types of weather.
  • Explain where clouds come from.
  • Describe what is happening inside the jar.
  • How did you make fog appear inside the jar?
  • What do you think might happen when the ice cube melts?

Explore, Extend & Integrate

  • Choose a foggy day to go outside with the children. Have them describe the fog; how does it feel, what does it look like, do they hear anything, what does it smell like, and do they taste anything if they open their mouths?
  • On a foggy day, keep an eye on the window and point out to the children when the fog begins to lift. Discuss where the fog goes as it disappears.
  • Keep track of the weather on a classroom calendar. Compare the amount of foggy days to rainy, windy, sunny, or snowy days.

Check for Children’s Understanding

  • Could children explain where clouds come from?
  • Could children describe what happened inside the jar?
  • Could children explain how the fog appeared inside the jar?


Did You Know?

Fog forms when there is a difference in temperature between the air and the ground with the cooler air currents passing over hot air pressure from moist land or a warm body of water. Since cool air cannot hold as much moisture as warm air, fog forms. In our activity, the cold air from the ice cubes collided with the warm, moist air from the hot water in the jar. These two different temperatures of air collided, causing the water vapor to condense and form a fog. Fog can also form when there is high humidity in the air coupled with enough water vapor in the air.

Fog is a cloud that has formed close to the Earth. Clouds are a collection of very tiny water droplets. The droplets are so tiny and lightweight, they float in the air. When billions of these tiny droplets come together, they form a cloud. In our activity, the tiny water droplets in the warm air were forced together by the cold ice, creating a cloud.

Vocabulary: Child-Friendly Definitions

  • fog – a thick cloud that is near to the ground.
  • weather – the conditions outside; including temperature, rain, snow, Sun, and other things.
  • cloud – a white or gray mass of small drops of water high in the sky above the Earth.
  • water vapor – water in the form of a gas; especially at a temperature below the boiling point.
  • air pressure – the force of air on things; the pressure of the Earth’s atmosphere.
  • current – a mass of liquid or air that flows in one direction.

Lesson Tips

Once the ice cubes are placed on the paper plate, fog will form and water droplets will gather on the glass. The process may take a few minutes for the fog to form.


  • Fog (Weather) by Helen Frost
  • Hide and Seek Fog by Alvin Tresselt
  • Pea Soup Fog by Constance Smith
  • The Foggy, Foggy Forest by Nick Sharrat

Home School Resources

Home educators: use these printable lesson PDFs to teach this lesson to your home schoolers. They're available in English and Spanish.

Home/School Connections

Las Conexiones a la Casa

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Content Provided By

Common Core State Standards Initiative – These lessons are aligned with the Common Core State Standards ("CCSS"). The CCSS provide a consistent, clear understanding of the concepts and skills children are expected to learn and guide teachers to provide their students with opportunities to gain these important skills and foundational knowledge [1]. Visit the CCSS