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Worksheet Grade 7 Social Studies & Civics

Water Use in the Ravensmere, Tarnsley, and Ingerfield Basins

A grade 7 worksheet comparing farm, household, and factory water use in three fictional river basins using percent shares and a drought cut.

Objectives

  1. Students will calculate each sector's percent share of a basin's total water withdrawal.
  2. Students will compare three regions by the pattern of their water use rather than by their totals.
  3. Students will explain why an equal percent cut affects two regions differently.

Vocabulary

Desalination
Turning salty water, like ocean water, into fresh water people can use. It works, but it takes a lot of energy and leaves behind very salty water that must be handled carefully.

Also: withdrawal, basin, sector, percent share

Teacher overview

Two regions can withdraw very different amounts of water and still face the same shortage, because what matters in a drought is who is using the water and for what. This worksheet gives students yearly withdrawal figures for three fictional river basins, one dominated by farming, one by cities, and one by industry. Students find each sector's percent share, compare the three patterns against the global pattern in which farming accounts for roughly 70 percent of the fresh water people withdraw, and then test what an equal percent cut would mean in two of the basins.

Water Use in the Ravensmere, Tarnsley, and Ingerfield Basins — Grade 7 Social Studies & Civics
Name: ____________________________ Date: ______________

Student Worksheet

Ravensmere, Tarnsley, and Ingerfield are three fictional river basins. The table shows how much water each basin withdraws in a year, in billions of gallons, and how that water is divided among three sectors.

Basin Farms Homes and cities Factories
Ravensmere 630 180 90
Tarnsley 120 360 120
Ingerfield 200 100 200

Show your work for each item.

  1. Add the three sectors to find Ravensmere's total yearly withdrawal.
  2. Ravensmere's farms withdraw 630 of that total. What percent of the basin's total goes to farms?
  3. Tarnsley withdraws 600 billion gallons in all, and 360 of that goes to homes and cities. What percent goes to homes and cities?
  4. Ingerfield withdraws 500 billion gallons in all, and 200 of that goes to factories. What percent goes to factories?
  5. Around the world, farming accounts for roughly 70 percent of the fresh water people withdraw. Which of the three basins is closest to that pattern?
  6. Ravensmere withdraws 900 billion gallons a year and Tarnsley withdraws 600. How many times as much does Ravensmere withdraw as Tarnsley?
  7. A drought rule cuts Ravensmere's 900 billion gallon total by 15 percent. How many billions of gallons must the basin give up?
  8. Suppose the whole cut in item 7 came out of the 630 billion gallons the farms use. What percent of farm use would that be? Round to the nearest whole percent.
  9. Ingerfield plans a desalination plant to supply 5 percent of its 500 billion gallon total. How many billions of gallons a year would the plant supply?
  10. A single drought rule cuts every basin by the same percent. Explain why that rule would change daily life in Ravensmere and in Tarnsley in different ways.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key

  1. Answer: 900 billion gallons.
    630 + 180 + 90 = 900 billion gallons withdrawn in Ravensmere each year.

  2. Answer: 70 percent.
    630 divided by 900 is 0.70, which is 70 percent.

  3. Answer: 60 percent.
    360 divided by 600 is 0.60, which is 60 percent.

  4. Answer: 40 percent.
    200 divided by 500 is 0.40, which is 40 percent.

  5. Answer: Ravensmere.
    Farms take 70 percent of Ravensmere's water, which matches the global share of roughly 70 percent. Tarnsley's farms take 20 percent and Ingerfield's take 40 percent.

  6. Answer: 1.5 times.
    900 divided by 600 is 1.5, so Ravensmere withdraws one and a half times as much as Tarnsley.

  7. Answer: 135 billion gallons.
    900 times 0.15 is 135 billion gallons that the basin must give up.

  8. Answer: 21 percent.
    135 divided by 630 is about 0.214, which rounds to 21 percent of farm use.

  9. Answer: 25 billion gallons.
    500 times 0.05 is 25 billion gallons a year from the planned plant.

  10. Answer: the cut falls mostly on farms in Ravensmere and mostly on households in Tarnsley.
    Because 70 percent of Ravensmere's water goes to farms, most of an equal percent cut lands on irrigation, harvests, and farm income. Because 60 percent of Tarnsley's water goes to homes and cities, the same rule mostly reaches lawns, showers, and businesses. Accept any answer that ties the difference to the sector shares in items 2 and 3.

Differentiation

Support (below grade level)

Give these students the row totals for all three fictional basins already filled in, so their work begins at the percent step. Provide a worked model using a fourth basin with a total of 400 and farm use of 100, showing that 100 divided by 400 is 0.25, or 25 percent.

Extension (above grade level)

Ask students to design a drought rule that cuts the same total number of billions of gallons from Ravensmere as the 15 percent rule does, but takes different percents from each sector, and to write two sentences defending the split to a basin board.

ELL supports

Pre-teach "withdrawal," "basin," and "sector" with a simple drawing of one river feeding a farm, a city, and a factory. Provide a percent frame that reads "part divided by total equals the share," and allow items 5 and 10 to be answered in short phrases supported by one number from the table.