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Worksheet Grade 7 Social Studies & Civics

Cranberry Landing's Tiered Water Rates: A Billing Worksheet

A grade 7 worksheet on a fictional utility's tiered water rates, where students compute household bills and see how block pricing rewards using less water.

Objectives

  1. Students will calculate a household water bill using a tiered rate structure and a service charge.
  2. Students will compare how charges grow as water use moves into higher-priced tiers.
  3. Students will explain how tiered pricing encourages households to conserve water.

Vocabulary

Water bill
The statement a household receives showing how much water it used and how much it owes. Reading it carefully can reveal hidden leaks and ways to save money.

Also: tiered rate, conservation, service charge

Teacher overview

Many water utilities use tiered rates, also called block rates, in which the price per gallon rises as a household uses more water, so that heavy users pay a higher rate on their extra gallons. This worksheet places students inside the fictional Cranberry Landing utility and its three-tier rate structure. Students calculate several households' monthly bills, then compare how the charges grow, ending with questions about why a utility would price water this way to encourage conservation.

Cranberry Landing's Tiered Water Rates: A Billing Worksheet — Grade 7 Social Studies & Civics
Name: ____________________________ Date: ______________

Student Worksheet

Suppose the fictional Cranberry Landing utility bills each household a fixed $12 service charge every month, plus a charge for the water used. The water charge follows three tiers:

  • Tier 1: the first 4,000 gallons cost $3 per 1,000 gallons.
  • Tier 2: the next 6,000 gallons (from 4,001 to 10,000) cost $5 per 1,000 gallons.
  • Tier 3: any water above 10,000 gallons costs $9 per 1,000 gallons.
  1. The Ramos household uses 3,000 gallons in a month. All of it is in Tier 1 at $3 per 1,000 gallons. What is their water charge, not counting the service charge?
  2. What is the Ramos household's total bill, including the $12 service charge?
  3. The Okafor household uses 8,000 gallons. The first 4,000 gallons are Tier 1 at $3 per 1,000, and the next 4,000 gallons are Tier 2 at $5 per 1,000. What is their water charge?
  4. What is the Okafor household's total bill, including the $12 service charge?
  5. The Whitfield household uses 12,000 gallons: 4,000 in Tier 1, 6,000 in Tier 2, and 2,000 in Tier 3. What is their water charge?
  6. What is the Whitfield household's total bill, including the $12 service charge?
  7. The Whitfield household used 1.5 times as many gallons as the Okafor household (12,000 versus 8,000). Did the Whitfield water charge come out to exactly 1.5 times the Okafor water charge? Show why or why not.
  8. Explain how a tiered rate structure gives households a reason to use less water.
  9. Suppose the Whitfield household cut its use from 12,000 to 10,000 gallons. By how much would its total bill drop?
  10. Which tier gives a household the strongest reason to conserve, and why?

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: $9.
    3,000 gallons is 3 units of 1,000 gallons in Tier 1: 3 × $3 = $9.

  2. Answer: $21.
    $9 water charge + $12 service charge = $21 total.

  3. Answer: $32.
    Tier 1: 4 × $3 = $12. Tier 2: 4 × $5 = $20. Total water charge = $12 + $20 = $32.

  4. Answer: $44.
    $32 water charge + $12 service charge = $44 total.

  5. Answer: $60.
    Tier 1: 4 × $3 = $12. Tier 2: 6 × $5 = $30. Tier 3: 2 × $9 = $18. Total water charge = $12 + $30 + $18 = $60.

  6. Answer: $72.
    $60 water charge + $12 service charge = $72 total.

  7. Answer: No.
    The Whitfield water charge is $60 and the Okafor water charge is $32, and $60 ÷ $32 = 1.875, not 1.5. Using 1.5 times as much water cost more than 1.5 times as much because the extra gallons fell in higher-priced tiers.

  8. Answer: As a household uses more water, its extra gallons cost more per 1,000, so the price of each additional gallon rises. A household that wants a lower bill has a clear reason to cut back before reaching the expensive higher tiers.

  9. Answer: $18.
    Cutting from 12,000 to 10,000 gallons removes the 2,000 Tier-3 gallons, which cost 2 × $9 = $18, so the total bill drops by $18.

  10. Answer: Tier 3.
    Tier 3 charges $9 per 1,000 gallons, the highest price, so cutting water use out of Tier 3 saves the most money and gives the strongest reason to conserve.

Differentiation

Support (below grade level)

Provide a printed tier chart with the price of each tier and a worked model bill before students begin. Allow calculators, and let students fill in a simple three-row table (Tier 1, Tier 2, Tier 3) for each household before adding the service charge.

Extension (above grade level)

Ask students to find the exact number of gallons at which a Cranberry Landing household's total monthly bill first passes $50, showing their tier-by-tier reasoning, and to explain what that gallon amount tells a family trying to stay under a $50 budget.

ELL supports

Pre-teach "tiered rate," "service charge," and "conservation" with a simple stair-step drawing showing the price rising at each tier. Provide the tier prices on a visible reference card, and allow questions 8 and 10 to be answered with short phrases supported by a specific price from the worksheet.