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Worksheet Grade 6 Social Studies & Civics

Ferndale's Water Bill: Converting CCF and Tiered Rates

A grade 6 worksheet where students convert a water bill's CCF units to gallons and compute tiered water rate charges for the fictional town of Ferndale.

Objectives

  1. Students will convert between CCF and gallons using the standard cubic-foot-to-gallon conversion.
  2. Students will calculate a household's water bill under a tiered rate structure.
  3. Students will explain why a city might charge different prices for different amounts of water used.

Vocabulary

Key words: CCF, tiered rate, unit rate, utility

Teacher overview

Many water bills in the United States do not list gallons. Instead, they show a unit called CCF, short for one hundred cubic feet, which is the unit many water meters record. This worksheet asks students to convert CCF to gallons and then apply a tiered rate structure, in which the price per CCF rises once a household crosses a usage threshold. Students may assume that every water bill charges one flat price for every unit used; under tiered pricing, the same household can pay two or three different rates within a single bill, one for each tier it crosses.

Ferndale's Water Bill: Converting CCF and Tiered Rates — Grade 6 Social Studies & Civics
Name: ____________________________ Date: ______________

Student Worksheet

The fictional town of Ferndale meters its water in cubic feet, then bills residents in CCF, where 1 CCF equals 100 cubic feet. Each cubic foot of water holds 7.48 gallons, so 1 CCF equals 100 × 7.48 = 748 gallons. Suppose Ferndale's water utility charges residents using this tiered rate structure:

Tier CCF used Price per CCF
Tier 1 0-10 CCF $3.00
Tier 2 11-20 CCF $4.50
Tier 3 Over 20 CCF $6.00

A household pays the Tier 1 price for every CCF up to 10, the Tier 2 price for every CCF from 11 to 20, and so on. Use these facts for every item below.

  1. The Alvarez household used 8 CCF this month. Convert their usage to gallons.
  2. A neighboring household used 1,496 gallons this month. Convert their usage to CCF.
  3. The Alvarez household's entire 8 CCF falls in Tier 1. What is their total water charge for the month?
  4. The Chen household used 15 CCF this month: 10 CCF in Tier 1 and 5 CCF in Tier 2. Calculate their total bill by adding the two tiers separately.
  5. In one or two sentences, explain why a city might design a tiered rate structure instead of charging the same price for every CCF a household uses.
  6. Ferndale's town council votes to raise the Tier 1 rate from $3.00 to $3.30 per CCF. What percent increase is that?
  7. Using the new Tier 1 rate of $3.30 per CCF, recalculate the Alvarez household's bill for their 8 CCF of use.
  8. A resident tells the town council that the tiered system is unfair to large families, who need more water for daily needs and so land in a higher tier. Do you agree or disagree with the resident? Support your answer with one reason.
  9. Complete this short rate table at the original Tier 1 price of $3.00 per CCF: what is the cost for 1 CCF, for 5 CCF, and for 10 CCF?

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: 5,984 gal.
    8 CCF × 748 gal/CCF = 5,984 gallons.
  2. Answer: 2 CCF.
    1,496 gal ÷ 748 gal/CCF = 2 CCF.
  3. Answer: $24.00.
    8 CCF × $3.00/CCF = $24.00, since all 8 CCF fall within Tier 1 (0-10 CCF).
  4. Answer: $52.50.
    Tier 1 portion: 10 CCF × $3.00 = $30.00. Tier 2 portion: 5 CCF × $4.50 = $22.50. Total: $30.00 + $22.50 = $52.50.
  5. Answer: Answers will vary. A strong response explains that charging a higher price once a household uses more water gives an incentive to conserve, while keeping the price lower for the water every household needs for basic daily use.
  6. Answer: 10 percent.
    The increase is $3.30 − $3.00 = $0.30. $0.30 ÷ $3.00 × 100 = 10 percent.
  7. Answer: $26.40.
    8 CCF × $3.30/CCF = $26.40.
  8. Answer: Answers will vary. A strong response either agrees, noting that a larger family needs more water for basic daily use and so reaches the higher-priced tiers even when each person uses little, or disagrees, noting that the tiered system still charges every household the same low Tier 1 price for its first 10 CCF and only raises the price on water beyond that.
  9. Answer: $3.00, $15.00, $30.00.
    1 CCF × $3.00 = $3.00; 5 CCF × $3.00 = $15.00; 10 CCF × $3.00 = $30.00.

Differentiation

Support (below grade level)

Provide a printed conversion strip showing "1 CCF = 100 cubic feet = 748 gallons" and a worked example of one tier calculation before students attempt items 3 and 4 independently. Allow calculators for every item, and let students answer item 8 by circling "agree" or "disagree" and completing one sentence starter: "I think this because ___."

Extension (above grade level)

Ask students to design their own three-tier rate structure for a town that wants to strongly discourage water use above 25 CCF per month, choosing their own prices, then calculate what a 30-CCF household would pay under their design compared to Ferndale's original rates.

ELL supports

Pre-teach "tier," "rate," and "convert" with a simple staircase drawing (each step is a tier, taller steps cost more per CCF). Provide the rate table already filled in as a reference card students can keep beside their worksheet, and allow item 5 and item 8 to be answered orally to a partner before writing.