High in a freezing cold cloud, a tiny drop of water freezes onto a speck of dust. Now it's a little bit of ice. As it falls through the cloud, more water freezes onto it, growing six frosty arms. It floats down to you as a snowflake!

Why does a snowflake have six arms?

Water is made of tiny bits called molecules. When water freezes, the molecules lock together in a pattern with six sides, a shape called a hexagon. So every ice crystal starts as a tiny hexagon, and its arms grow out from the six corners.

Why does every snowflake look different?

Each snowflake takes its own path down through the cloud. On the way, the air around it gets a little colder or warmer, and a little wetter or drier. Every change makes its arms grow a new way. No two flakes take the same trip, so no two grow quite alike.

How is snow made?

Roo answers for ages 4–11, then goes 2 steps deeper each time a child asks why.

Roo says

High in a freezing cold cloud, a tiny drop of water freezes onto a speck of dust. Now it's a little bit of ice. As it falls through the cloud, more water freezes onto it, growing six frosty arms. It floats down to you as a snowflake!

For ages 4–7

Checked against How do snowflakes form? (NOAA)
Why does a snowflake have six arms?

Water is made of tiny bits called molecules. When water freezes, the molecules lock together in a pattern with six sides, a shape called a hexagon. So every ice crystal starts as a tiny hexagon, and its arms grow out from the six corners.

For ages 6–9

Checked against How do snowflakes form? (NOAA)
Why does every snowflake look different?

Each snowflake takes its own path down through the cloud. On the way, the air around it gets a little colder or warmer, and a little wetter or drier. Every change makes its arms grow a new way. No two flakes take the same trip, so no two grow quite alike.

For ages 8–11

Checked against How do snowflakes form? (NOAA)