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Lesson plan Grade 9 Social Studies & Civics

Funding Draymoor's Aging Water Mains: A Grade 9 Trade-off Lesson

A grade 9 civics and economics lesson where students act as budget analysts and weigh a rate increase against a bond to fund a fictional city's pipe replacement.

Objectives

  1. Students will calculate the per-household cost of two ways to fund water main replacement.
  2. Students will explain the trade-off between paying now through rates and borrowing through a bond.
  3. Students will evaluate a reactive repair policy in terms of its intended and unintended outcomes.

Vocabulary

Water main
A big underground pipe that carries drinking water beneath the streets to a neighborhood. Smaller service lines branch off it to reach each building.
Deferred maintenance
Repair work that keeps getting put off to save money now. The longer it waits, the worse and more expensive the problems become.

Also: bond, rate increase, affordability

Teacher overview

Buried water pipes fail slowly and out of sight, so the cost of replacing them is easy for a city council to postpone. In this lesson students act as budget analysts for the fictional city of Draymoor, which must decide how to pay for replacing pipes that engineers say are past their useful life. Students compare a pay-as-you-go rate increase against a long-term bond, then evaluate the city's current habit of waiting for pipes to break before fixing them. The common misconception this lesson corrects is that a "small" annual rate increase is trivial; students discover that the same replacement can cost a household more or less depending entirely on how the city chooses to pay for it.

Procedure

Hook (8 min): Ask students to estimate how often a water main breaks somewhere in the United States. After a few guesses, share that a main breaks roughly every two minutes, and that the American Society of Civil Engineers gave the nation's drinking water infrastructure a C- on its 2025 report card. Explain that most of these pipes sit underground for decades, so the bill for replacing them arrives long after the pipes were installed.

Direct instruction (12 min): Introduce two terms on the board: a rate increase, which raises what every customer pays each month, and a bond, which lets a city borrow a large amount now and repay it with interest over many years. Explain that the federal government estimates about $625 billion in drinking-water investment is needed over 20 years, with roughly two-thirds of that for distribution pipes, so cities across the country face the same choice the city of Draymoor faces. Emphasize that a bond spreads the cost over time but adds interest, while a rate increase avoids interest but asks today's customers to pay the full amount sooner.

Guided practice (10 min): Work the first handout scenario together. Model how to find Draymoor's total replacement cost by multiplying the miles of failing pipe by the cost per mile, and write each step so students can follow the units. Pause for a quick thumbs-up or thumbs-down poll: "Do you understand why 60 miles at $1.2 million per mile gives $72 million?" If more than about a quarter of the class signals thumbs-down, rework the multiplication before moving on.

Independent practice (15 min): Students complete the remaining Student Handout questions individually or in pairs, calculating the annual and per-household cost of each funding option and comparing them. Circulate and check that students are dividing by the right number of households and years.

Closure and exit ticket (10 min): Bring the class together to name which option costs a household less each year and which costs less in total. Then pose the evaluation question as an exit ticket: "Draymoor now spends nothing on planned replacement and only repairs mains after they break. Name one unintended consequence of continuing that policy." Collect the tickets and scan for answers that identify a real downside, such as emergency repairs costing more or service outages hitting residents without warning.

Funding Draymoor's Aging Water Mains: A Grade 9 Trade-off Lesson — Grade 9 Social Studies & Civics
Name: ____________________________ Date: ______________

Student Handout

The fictional city of Draymoor owns 240 miles of water main. Engineers report that 60 of those miles are past their useful life and should be replaced over the next 10 years. Replacing one mile of main costs about $1.2 million. Draymoor has 20,000 households that pay water bills. Use these figures for every question, and show your work.

  1. What is the total cost to replace all 60 miles of failing water main?
  2. Option A is a rate increase that spreads the total cost evenly across 10 years. What is the cost the city must raise each year under Option A?
  3. Under Option A, how much of that annual cost falls on each of the 20,000 households in one year?
  4. Option B is a 30-year bond. With interest, the city repays a total of about 1.5 times the amount it borrows, spread evenly across 30 years. Under Option B, how much does each household pay per year?
  5. Compare Option A and Option B. Which costs a household less per year, and which costs Draymoor less in total? Explain the trade-off a council member would weigh.
  6. A Draymoor household earns $40,000 a year and already pays $600 a year for water and sewer service. A widely used rule of thumb, built from two EPA benchmarks, treats combined water and sewer costs above about 4.5% of household income as a high burden. After adding Option A's yearly amount to the $600, what is the household's new water-and-sewer cost, what percent of its income is that, and is it above the 4.5% threshold?

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: $72 million. For the city of Draymoor, 60 miles multiplied by $1.2 million per mile equals $72 million.
  2. Answer: $7.2 million per year. The $72 million total divided evenly across 10 years is $7.2 million each year.
  3. Answer: $360 per household. The $7.2 million annual cost divided among 20,000 households is $360 per household in one year, or about $30 a month.
  4. Answer: $180 per household. With interest the city repays about 1.5 times $72 million, which is $108 million; divided across 30 years that is $3.6 million a year, and divided among 20,000 households that is $180 per household each year.
  5. Answer: Option B costs less per year ($180 versus $360), while Option A costs less in total ($72 million versus $108 million). Accept any answer that names this trade-off: the bond lowers the yearly bill but adds interest, and it shifts part of the cost to future residents who will also use the new pipes, while the rate increase is cheaper overall but asks today's households to pay more now.
  6. Answer: $960 a year; that is 2.4% of income, below the threshold. Adding Option A's $360 to the current $600 gives $960 a year; $960 divided by $40,000 income is 0.024, or 2.4%, which is below the 4.5% high-burden threshold.

Differentiation

Support

Provide a partially completed calculation sheet with the first scenario already worked for the fictional city of Draymoor (60 miles times $1.2 million equals $72 million) and labeled blanks for the division steps, so students focus on the reasoning rather than setting up each operation. Allow calculators for every item.

Extension

Ask students to work out, using only the figures in this lesson, how the answer to question 6 would change if the city chose Option A during a year when combined bills had already risen. Have them write a short recommendation to the Draymoor council stating which funding option they would choose and defending it with at least two numbers from the handout.

ELL supports

Pre-teach "water main," "bond," "rate increase," and "affordability" with a simple labeled diagram of a pipe under a street and a picture of a monthly bill. Provide sentence frames for question 5 ("Option ___ costs less each year because ___. Option ___ costs less in total because ___.").

Extensions

Invite a staff member from your local public works department or water utility to describe how your community actually pays for pipe replacement, and whether it uses rate increases, bonds, grants, or a mix. Students can compare the real answer to the two options they modeled for Draymoor and note which trade-offs the local utility said mattered most.