Hands-on Activity: Snow vs. Water
Educational Standards :
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
To share with the entire class:
Introduction/Motivation (Return to Contents)
When you think of water, what comes to mind? How is it used? What is the closest source of water to your house, your school? Did you know that about 75% of the Earth is covered in water? Where is all this water located? Water on the Earth can be found in the oceans, rivers, lakes, atmosphere and underground — in areas called aquifers. The salty oceans are the largest source of water, containing 97% of the Earth's total water.
How much of the Earth's water is fresh water? Well, if 97% of the Earth's water is salty ocean water, then that leaves about 3% percent of water on Earth as fresh water. The salt in ocean water makes it unsafe to drink, unless engineers remove the salt. Because of this, finding fresh water is becoming more and more important as people begin to understand how clean water is better for us to drink. The Earth's fresh water resources come in different forms. About 2.14% of the fresh water of Earth is found in ice caps and glaciers; 0.61% is in groundwater aquifers, and the remaining 0.0091% makes up rivers and lakes. (Draw a pie chart on the board, listing these percentages. Have students copy the graph to illustrate the distribution of water on Earth, and have them dicuss where they think their drinking water comes from.) The demand for clean drinking water is also increasing as the Earth's population increases. Very little of the Earth's water is suitable for drinking; it is the job of environmental engineers, therefore, to figure out how to make water safe for drinking, as well as locate it and deliver it to communities that are not near a water source.
We get most of our drinking water from rivers, lakes and groundwater, but what if you are not located near a water source? Another way to get drinking water is from the atmosphere (i.e., rain and snow). Can you get water from snow during the summer? Well, actually you can! Think about snow that has fallen very high on a mountain and sits there all winter. It becomes packed solid and stays extremely cold. When spring and summer arrive, that snow high up starts to melt and runs down the sides of the mountains into rivers and streams. This source of water is called snowmelt. Snowmelt can be any runoff of water from melting snow: in the mountains, off a roof or on the ground. Snowmelt in the spring and summer actually provides a great source of fresh water for a lot of communities. It is estimated that around 75% of water used in the western United States is from stored up snowmelt.
Environmental engineers help us design and build the systems to find, gather and clean water sources for use in our homes. In fact, environmental engineers design the water treatment plants that remove nasty germs and bugs from fresh water sources, allowing for suitable water for us to drink. They also develop the treatment plants that clean up water once it is flushed down our drains or toilets. Engineers must understand how fresh water from snowmelt is carried in our rivers and lakes so that they are knowledgeable to build dams, reservoirs and water treatment plants. Today, we are going to be environmental engineers and learn a little more about what happens during snowmelt and how we should design a water treatment plant for changing snowmelt into drinking water.
Procedure (Return to Contents)
Before the Activity
With the Students
Attachments (Return to Contents)
Troubleshooting Tips (Return to Contents)
Make sure students know that the first time they fill their cups with snow not to pack the snow in.
It is also good to put their cups in a warm place, near a heater or in a window, so they melt quickly.
Assessment (Return to Contents)
Discussion Question: Solicit, integrate and summarize student responses.
Prediction: Have students predict the outcome of the activity before the activity is performed. Have them record their predictions on a piece of paper or record the class totals on the board.
Activity Embedded Assessment
Worksheet: Have the students record measurements and follow along with the activity on their worksheet. After students have finished their worksheet, have them compare answers with their peers. Ask them again if they think one cup of snow produces an equal amount of water? Why not? (Answer: No; snow is less dense.)
Thumbs up/thumbs down: Ask a question and have students vote by holding thumbs up for agree and thumbs down for disagree. Count the votes and write the totals on the board. Give the right answer.
Engineering recommendations: Have students think about what the activity means in terms of engineering a drinking water treatment plant, especially how the water yield from snow is less than from other fresh water sources. (Note: remind them that a certain amount of snow actually equals less water.) How would an engineer use what they learned today about snowmelt when designing a water treatment system? For example, if there is 10 ft. of snowfall, should the engineers design for 10 ft. of useable water? Should the engineers design the system to collect snowmelt in the winter or spring? Have the students list two or three ideas on a piece of paper from today's activity that would help in designing a water treatment plant for snowmelt.
Activity Extensions (Return to Contents)
Take a closer look at a snowflake: Take black paper or fabric and put it in the freezer. Once frozen, take it out of the freezer and place it outside when it's snowing. Let some snowflakes land on the paper and quickly use a magnifying glass to see the beautiful shapes. Alternatively, freeze a piece of glass and a can of hairspray and wait for the snow to fall. Spray the frozen glass with the frozen hairspray and let some snowflakes settle on the glass. Bring the glass inside to thaw for 15 minutes and you will have a permanent record of your snowflakes. Doing the second variation on different snow days may give you a variety of the different types of snowflakes.
Have students visit the U.S. Library of Congress' website on snowflakes and investigate the different types/shapes: http://www.loc.gov/rr/scitech/SciRefGuides/snowflake.html#internet.
Activity Scaling (Return to Contents)
For lower grades, do the activity as is.
For upper grades: Have the students also measure the temperature of the snow before it melts and after it melts. How might this affect the design of a drinking water treatment plant?
References (Return to Contents)
TheTeachersCorner.net, Thematic Units, "Ice and Snow Fun," accessed June 27, 2006. http://www.theteacherscorner.net/thematicunits/iceandsnow.htm
ContributorsSara Born, Malinda Schaefer Zarske, Janet Yowell
Copyright© 2006 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of these digital library curricula were developed by the Integrated Teaching and Learning Program under National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.