Students will use 10 liters (approximately 2.5 gallons) of water to
represent all the water on the earth. They will be given the
percentage for each water source in relation to the total amount,
and asked to divide the 10 liters of water to demonstrate this.
For each group of students:
- 10 liters of water
- 2.5 gallon water container (to hold the 10 liters)
- Graduated cylinders
- Eye dropper
- 6 small clear containers (e.g., pint jars)
Background for Teachers
To identify the reservoirs of the Earth's water cycle (e.g., ocean,
icecaps / glaciers, atmosphere, lakes, rivers, biosphere, ground
water) locally and globally and graph or chart relative amounts in
Approximately 72 percent of the earth is covered with water.
Sources of water are the oceans, icecaps and glaciers, groundwater, freshwater lakes, inland seas and salt lakes, the atmosphere,
and rivers. In this activity, 10 liters of water in a bucket are used
to represent all the water on the earth. See the table below for the
percentage of each water reservoir in relation to the total amount,
and the appropriate measurement for each reservoir
||APPROXIMATE % OF THE TOTAL AMOUNT
||All water left in bucket
|Icecaps / glaciers
|| ~ 200 ml
||~ 70 ml
|| ~ 3 ml
|Inland seas / salt lakes
||~ 4 drops
||~ 1 drop
The percentage of usable freshwater is reduced by pollution and
availability (location). Therefore, the actual amount of water that is
usable by humans is very small (approximately 0.00003 percent).
Intended Learning Outcomes
- Use Science Process and Thinking Skills
- Construct models, simulations and metaphors to describe and explain natural phenomena.
- Use mathematics as a precise method for showing relationships.
- Communicate Effectively Using Science Language and Reasoning
- Use mathematical language and reasoning to communicate information.
- Show the students a map of the world or the globe. Ask them what the color blue represents (water). Ask them what percentage of the globe/earth is covered in water (72%). Is it all usable by humans? (No)
- Ask the students to identify the various reservoirs of water on
the earth other than oceans. As they give answers, make a list on
the board in the front of the room. Students' responses may include reservoirs like dams, which would be included with lakes or
rivers; wells, which come from groundwater; springs, which may
be included in rivers, and so forth. The final list should be icecaps
/ glaciers, groundwater, freshwater lakes, inland seas / salt lakes,
atmosphere, and rivers.
- When the list on the board is complete, pass out the water distribution worksheet (pdf) and divide the students into groups.
- Give each group 10 liters of water in a bucket (approximately
2.5 gallons), graduated cylinders, an eye dropper and six small
clear containers. Explain that the 10 liters represent all the water on
- Have the students label the six small containers with the various
water reservoirs (icecaps / glaciers, groundwater, freshwater lakes,
inland seas / salt lakes, atmosphere, and rivers).
- Ask the students to estimate the percentage of water in each
reservoir. Have them measure the appropriate amount of water
for each reservoir and record their data on the water distribution
worksheet. Remind them that they will leave the ocean water in the
- Discuss the results of the groups' estimations. Where did they
think most of the water was located? Is there more water in rivers
or in the atmosphere?
- After discussing the initial estimations, demonstrate to the class
the actual amounts found in each reservoir (found on the table on
the first page of this activity). Be sure to have the class fill in the
correct amounts on the student worksheet.
- How much of the water on the earth is actually available for
Logically, one would assume if you added the percentage of
usable water sources, you would find the total amount of
usable water. This does not work out to be true because the
amount is reduced by pollution and availability (location).
The actual amount is approximately 0.00003 percent.
- How can students conserve water?
There are many ways students can conserve water. Discuss
the following tactics with your students:
- Don't leave the water running while brushing your teeth.
- Limit your showers to 10 minutes or less.
- Look around your house for leaky faucets. Ask your parents to fix them immediately.
- Keep a pitcher of water in the refrigerator so you don't
have to run the faucet and wait for the water to cool.
- Clean your sidewalks with a broom, not a hose.
- Wash your car or dog on the lawn instead of the driveway.
This way your lawn gets watered too.
- Only wash full loads of dishes and laundry.
- How can students help reduce pollution to the already small amount of water that is available for human use?
- Don't use excessive amounts of fertilizers or pesticides around your house. They can wash into the storm drains and end up in a stream.
- Never put something down a storm drain that may hurt a fish.
- Don't be a litter bug. Always dispose of trash in a proper container, not in the water.
- Make sure that your family car doesn't leak oil or antifreeze. This can wash into the water and be dangerous for fish, birds, even cats and dogs.
- Walk only on existing trails when near the water to help reduce erosion.
Lesson plan authors: Andree Walker and Nancy Mesner (Utah State University Water Quality Extension)
This curriculum was made possible through funding from the Environmental Protection
Agency, the United States Department of Agriculture, Cooperative State Research,
Education, and Extension Service, the Utah Division of Wildlife Resources, and Utah
State University Extension.
Additional resources can be found on the USU Stream Side Science 9th Grade Curriculum web page.