The first night it gets cold enough to freeze water marks a huge change for everyone living outside.
What to look for: 2 things!

1. World's smallest
skating rink!

As the weather cools, your class will want to establish your "official ice-on bucket." Fill the bucket almost full of water and leave it outdoors in a spot it can remain. Check the bucket each morning. The day that the bucket is covered (a solid skim) with ice is your official "ice on" date.

 2. Is there ice on your local lake or pond?

Be sure to tell us when there ice covering all the way across your local pond or lake (or stream). This date will depend quite a bit on the size and depth of the lake (see about how ice forms below!).

Watch in your neighborhood and around school. If you think you are the first person to see thess events, ask your teacher to submit your name to the Wolf Ridge website (see table below.)
Where in the world do lakes freeze in winter?
This map shows how planet Earth might look from space in winter, looking straight down at the North Pole. The white areas would be covered with snow and ice in an average winter.

Where is North America? Can you find the Great Lakes? Where would you be on this map? We are used to seeing maps of the Earth from a certain angle. This is a good reminder that North America isn't always in the center of the view!

Image courtesy of the National Snow and Ice
Data Center, University of Colorado, Boulder.

Why doesn't ice sink?

A solid that doesn't sink?

When most substances freeze, they take up less space, making them more dense than their liquid form. This means most solids sink. Not so with water! Water actually EXPANDS when it freezes. Since frozen (solid) water is lighter than the same amount of liquid water, ice floats.

This is a lucky thing for the fish, turtles, frogs, insects, and other critters. They can survive winter, cozy in the warmer water below the layer of ice .
Cool Facts
Heat of Fusion

It takes the same amount of energy loss to lower the temperature of a bucket of liquid water 80 degrees Celsius as it does to change the same bucketful of liquid water into ice. This "heat of fusion" is what makes ice work great to keep pop cold in your cooler on a hot summer day.
O2
 Oxygen Heaven

Cold water holds more oxygen than warm water -- great news for animals trapped under the ice for the winter!

No Place like Earth!

Earth is the only place we know of in the whole universe where temperatures are just right so that water can be a mixture of solid (ice), liquid (lakes, rivers, ground water . . .), and gas (clouds, humid air . . .)

Think About It!
  1. Is there a river, lake, or pond near your school or home? What animals living there will need to survive winter under the ice?
  2. What do animals (and plants) drink when all of the water is frozen into ice?
Explore the Web
What makes water so special? Read this, then take the quiz!
Follow the water cycle and more.
Learn more about ice and snow in these Wolf Ridge classes:
Frozen Lake Study is a great class to take if you want to learn about whats' going on under the ice in the winter. You will hike to Wolf Lake, spend time in the "dark houses" (so you can see into the water), ice fish, cut ice, do some scientific tests, and have a great time.
Take Basic Survival to test your ability to stay warm, build a shelter, and make a fire with just a few items to work with. You'll learn lots about snow and your own abilities.
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