Let It Snow!
by Kim Moldofsky, The Maker Mom
With the exception of Jack Frost’s early appearance in Chicago, the weather has been unseasonably mild. But snow is already falling hard in some parts of our country. Snow is great fun for kids. As an adult with a long driveway to shovel, snow is less thrilling than it used to be. Yet, I still experience a certain excitement and a sense of wonder catching and examining individual white flakes.
It’s fascinating to inspect the single flakes. But curious minds want to know more. The definitive online guide to understanding snowflakes can be found at SnowCrystals.com, a site run by Caltech physicist, Kenneth G. Libbrecht. He studies “the molecular dynamics of crystal growth, including how ice crystals grow from water vapor,” AKA snowflakes. His site is full of stunning photos of flakes along with activities and tips for photographing the delicate frozen crystals. The site also provides everything you need to know to hold a snowflake scavenger hunt. I can’t think of a better way to learn to distinguish capped columns from stellar dendrites.
As Libbrecht points out in this morphology diagram, the flakes in the air are weather-dependent. A snowflake’s shape varies based on temperature and humidity changes that it experiences from the time it forms until it hits the Earth. It’s not impossible to find two matching snowflakes; it’s just that each flake develops under a unique set of atmospheric conditions. So they tend not to look alike.
Snowflakes are also a good study in symmetry. Six-sided flakes have rotation and reflection symmetry. Rotation symmetry means that the flake looks the same when you rotate it less than a full turn. Given their six-sided nature, they have six-fold symmetry. And speaking of folding, if you fold a six-sided flake in half, the two halves mirror each other, which is an example of reflection symmetry.
Making paper snowflakes is a popular winter pastime and a nice way to decorate a classroom. As your students seek to replicate flakes, be sure to note that snowflakes are hexagonal. You won’t see an 8-sided snowflake in nature! (On the other hand, if you need to keep someone occupied, send them out to hunt for one of these mythical creatures.)
Given the premiere of a certain popular science fiction movie, students might be a bit more excited about these Star Wars themed Snowflakes right now. Here are two great sites with free downloadable patterns.