March 29, 2024
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Activity helps children understand insulating quality of snow

It is a bitter cold January day, the air temperature barely rising through the afternoon from a morning low of -25?F. But in the silent layer next to the ground, beneath deep snow, a mouse nibbles a seed while keeping watch for predators. The temperature in this subnival layer is just below freezing, about 30 degrees Fahrenheit.

Many small mammals spend the winter in darkness, tunneling for food beneath the snow where a latticework of ice and air spaces keeps the earth’s warmth in and the cold out. This insulated environment is essential to the survival of shrews, moles, voles and mice.

These small mammals would surely freeze to death if exposed to the air for very long. Because of the relatively large surface area of their bodies in proportion to their volume, the heat lost upon exposure to severe cold cannot be replaced fast enough. And they do not have a thick enough coat to withstand continual exposure to subfreezing temperatures.

The activities described below are designed to help children understand the insulating value of snow, and to see firsthand whether there really are animals living beneath the snow.

Materials

Thermos bottle

Steaming hot water

Measuring cup

Gelatin

Film canisters (2 per group, half with covers)

Thermometers (2)

Site markers (sticks or yarn)

Seeds and nuts

The Activities

Find a clearing in the woods or perhaps a corner of your own property where the snow is at least a foot deep. Gather the children together to watch as you stir, until dissolved, one tablespoon gelatin into 1 cup of hot water, then fill the film canisters half-full.

Divide the children into small groups of two or three, and ask each group to choose two sites: a shady exposed area for one canister, deep snow in which to bury the other canister. When the sites are chosen, instruct the children to place the surface canister uncovered on top of the snow and the under-snow canister, with the lid securely fastened, beneath the snow. Nearby, place one thermometer on top of the snow, and bury the other thermometer under the snow at ground level. Mark the sites of buried canisters.

When the surface canister begins to gel, have the children dig up the buried containers and compare the progress of the two. Which canister gelled first? Why? Why might a mouse want to stay under the snow on a cold day? Check the thermometers. Is there a temperature difference? How much?

(Of course, one hopes that the surface canister will lose its heat more rapidly and gel first, and that the thermometer readings will reflect a significant difference in temperature between the surface of the snow and the ground beneath the snow. Leaving the cap off of the surface canister while covering the buried canister is cheating a little, but it speeds up gelling of the first, and keeps snow out of the second.)

When finished with this activity, have the children look for signs of animal activity in the snow, either holes or tunnels. Then let them dig some tunnels in the snow and leave some seeds or nuts in them. Return in a few days to see if any have been eaten.


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