Make a snowflake: http://www.highhopes.com/snowflakes.html
What are snowflakes? Snowflakes are made of ice crystals. Each snowflake is six-sided and made of as many as 200 ice crystals. Snowflakes form in clouds where the temperature is below freezing. The ice crystals form around tiny bits of dirt that has been carried up into the atmosphere by the wind. As the snow crystals grow, they become heavier and fall toward the ground.
(By the way, all of the posts from numbered 1- 25 are part of an Advent calendar for a friend from school; most of the words are borrowed from other websites.)