GEAR UP FOR LIFE
Unit S3 Math: Earth's Water

 

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Water on Earth

Water source Water volume, in
cubic miles 		Percent of
total water
Oceans 317,000,000 97.24%
Icecaps, Glaciers 7,000,000 2.14%
Ground water 2,000,000 0.61%
Fresh-water lakes 30,000 0.009%
Inland seas 25,000 0.008%
Soil moisture 16,000 0.005%
Atmosphere 3,100 0.001%
Rivers 300 0.0001%
Total water volume 326,000,000 100%
Source: Nace, U.S. Geological Survey, 1967
What is a cubic mile, or a cubic inch, or a cubic yard? Lots of people need to know cubic measures. For example, if you work with cement, you will certainly need to know the formula in order to create sidewalks, pads, or other structures. Builders, architects, engineers, repairmen and many other professionals need to know how to measure volume in cubic measures.
Click the Math Mentor icon to find out more about cubic measures before you continue.

Even if you don't need it in your work, it's just fun to learn about how to measure volume and other items. Learning is fun.

In this unit, we learned about water. What does the Water on Earth chart above tell you? The chart is formed like a table, but not the kind you eat on! A table has rows going left and right, and columns going up and down. A cell is a place where a column meets a row. You find specific information in a cell.

COLUMN

(ALL small boxes like this one in a table are cells)

  
     
     

ROW ->

    
     
     

Thinking Further

1. What do the three columns in the Water on Earth table tell you?

2. What do the three rows in the Water on Earth table tell you?

3. Fill in the answers by looking at the Water on Earth table, above.

a.. How much water volume does the Earth's atmosphere have?

b. What percentage of total water on Earth is held in icecaps and glaciers?

c. Which holds more water, rivers or soil moisture (humidity).

c. Where is the most and the least water held?

d. What is the total of water on Earth?

4. If you have access to a public or private pool in your area, write the dimensions of the pool and figure out how much water it might hold.

5. If you go by a construction site, ask for the dimensions of the hole they are digging for the foundation so that you can estimate how much cement or dirt they need to use.

PERCENTAGES

How can we think about percentages? What do they mean?

Percentages let you imagine amounts in relation to the whole. The whole is always 100%, no matter what the amount.

For example, the total water on Earth is 326,000,000 cubic miles. In percentages, that means that 326,000,000 cubic miles is 100%.

To find out what percentage of the total water volume on Earth is held in the oceans, you would multiply the amount of water in the oceans by the total amount.


  326,000,000 (the part)
____________

  317,000,000 (by the whole)

326,000,000 ÷317,000,000 = 0. 972392 (or rounded to .972). If you state that number as a percentage, it would be 97.2% (.972 X 100 for percentage).

Read more about how to read and interpret percentages (%) and try some exercises to practice. The Percentages Mentor has three parts.

1. 2. math icon 3. math icon

Once you complete all of the mentor exercises, you should be able to fill in the missing parts of the table without referring to the original! Try it!

Water on Earth

Water source Water volume, in
cubic miles 		Percent of
total water
Oceans 97.24%
Icecaps, Glaciers 7,000,000
Ground water 2,000,000  
Fresh-water lakes 0.009%
Inland seas 25,000
Soil moisture 0.005%
Atmosphere 3,100
Rivers 0.0001%
Total water volume 100%
Source: Nace, U.S. Geological Survey, 1967

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