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Science: My Dream Lesson - Getting the drift

Imagine the wonder that creating snow would inspire

Imagine the wonder that creating snow would inspire

Wouldn't it be great if you could create snow in the classroom, just for fun, just to see if you could? To do this you would have to build an insulated lab with a very high ceiling where you could reduce the temperature to -40degC.

To make snow fall you need to create a cloud at the top of the lab, using a humidifier to pump in air saturated with water vapour. To get small droplets to form and snowflakes to grow there need to be nucleation sites in the cloud (small particles around which water can condense and freeze).

The easiest way of doing this is to introduce some smoke into the cloud. Tiny ice crystals grow rapidly in super-saturated air, and fall very slowly. As they grow larger they fall faster, overcoming air resistance; the higher the lab is, the bigger the snowflakes.

If you can't afford to build your own cloud lab, you could try creating another interesting ice phenomenon: ice spikes. Fill a household ice-cube tray with distilled water and put it in a freezer. Often, vertical ice spikes grow out of the cubes. The water freezes from the edges and the surface of the cube can be almost frozen, with just a small hole. Freezing water from the middle of the cube expands and pushes through the hole, creating small spikes.

James Williams is a lecturer in science education at Sussex University's school of education and social work.

For more on growing snowflakes visit http:bit.lyAwL4

What else?

To get students to develop their own snow and ice experiments, try stap1987's "Investigating Snow" lesson plans.

Snow has caused chaos in England over the past few years: is global weather changing dramatically? Explore the causes and effects of climate change with the TES environmental collection.

Use fun activities to get pupils thinking about changing water states with Wordy William's "Water Cycle" activity pack.

In the forums

In the science forum, a teacher asks "What would you have in your ideal science lab?", while another is looking for quotes about science to use as classroom displays.

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