Students investigate weather-related phenomena including the cause of rain, evaporation, snow, and wind. Students also explore how a coat helps us stay warm in the cold and how blocking the sun to make a shadow causes the temperature to decrease.

What makes it snow?

Students watch a video of a snowflake forming and use cotton swabs to make a model of a snowflake to investigate the question: What makes it snow?

Objective

Students will be able to explain that snowflakes form from ice crystals in clouds. They will make a model to show the common six-sided structure of a snowflake. Students will also recognize snow as a solid form of water.

Key Concepts

• Clouds can be made up of either water droplets or a combination of water droplets and ice crystals.
• If the temperature is cold enough and there is enough moisture in the air, the ice crystals from the cloud can grow into snowflakes as they fall.
• Most snowflakes have six arms or branches with the same structure. This gives the snowflake symmetry.

NGSS Alignment

• K-ESS2-1: Use and share observations of local weather conditions to describe patterns over time. 
  The activities in this lesson focus on where and how snowflakes are formed. Students will understand the connection between clouds, temperature, ice crystals and snow, and will recognize the pattern of conditions necessary for snow to fall.

Summary

• Students are shown a video of snow falling and discuss their experiences in snow.
• Students discuss where they think snow comes from and how snowflakes are formed.
• Students see an animation of ice crystals in a cloud and a snowflake forming.
• Students see video of actual snowflakes forming and pictures of snowflakes with six similar branches or “arms.” Students then model the formation of a snowflake using cotton swabs.

Evaluation

There is no formal student activity sheet or assessment for this lesson. To evaluate student understanding, use your usual methods of interacting with students, asking questions, and discussing ideas with students as they participate in the different parts of the lesson.