Lesson plan Grade 7 Social Studies & Civics
Who Pays for Tarrowfield's Fire Hydrants?
A grade 7 economics lesson on a fictional town's hydrant costs, in which students compute the yearly cost per account and argue over who should pay for fire protection.
Objectives
- Students will calculate the yearly cost of hydrant maintenance per water account.
- Students will explain why households that never have a fire still pay for hydrants.
- Students will argue whether one large customer should pay the extra cost its needs create.
Vocabulary
- Fire hydrant
- The sturdy outlet on a water main that firefighters connect their hoses to. Utilities also use hydrants to flush pipes and test how much water the system can deliver.
- 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.
Also: fire flow, fixed cost, public good, water account
Teacher overview
Fire hydrants belong to the water system, not the fire department, and the water utility pays to test, flush, paint, and repair them whether or not anyone uses them. Because a hydrant that is never opened still costs money every year, hydrants raise a standing question in public finance, which is how a community should pay for protection that is available to every property and drawn on by very few. This lesson works through the hydrant budget of the fictional town of Tarrowfield and then asks students to decide whether a warehouse that needs a larger main should pay the difference itself. The point the arithmetic makes is that the cost of a hydrant lies in owning and maintaining it rather than in using it, so a service that is rarely called on is not therefore a cheap one to provide.
Procedure
Hook (5 min): Ask students to estimate how many times per year a fire hydrant in their town is actually opened by firefighters. Collect a few numbers, then ask what they think a town spends on hydrants in a year. Record the range without correcting it.
Direct instruction (12 min): Explain that hydrants are part of the water distribution system and are maintained by the water utility. Describe what that maintenance involves: checking that the valve turns, flushing the barrel, replacing gaskets, repainting, and repairing hydrants struck by vehicles. Explain the second cost that fire protection imposes, which is pipe size. A main sized only for drinking water is too small to deliver the flow a fire needs, so mains in commercial areas are built larger and cost more. Introduce the fictional town of Tarrowfield, its 900 hydrants, and its 5,000 water accounts.
Guided example (8 min): Model a cost-per-account calculation with numbers that do not appear on the handout. Suppose a different fictional town spends $60,000 a year on hydrants and has 4,000 accounts. Work through $60,000 divided by 4,000 to get $15 per account per year, then divide by 12 to get $1.25 per month. Ask students whether $1.25 a month sounds like a lot, and hold the question open.
Independent work (18 min): Students complete the eleven handout items. Watch for two errors on item 6: dividing the difference by the larger cost instead of the original, and answering with the dollar difference rather than a percent.
Closure and exit ticket (7 min): Take a standing vote on the warehouse question in items 9 and 10, then ask each student to write one sentence on an index card giving the strongest argument for the side they did not vote for. Collect the cards. If fewer than half the cards state the opposing argument in a form its supporters would accept, spend the first ten minutes of the next class rebuilding both cases on the board.
Student Handout
The fictional town of Tarrowfield owns 900 fire hydrants. The fictional Tarrowfield Water Department maintains them and bills 5,000 water accounts. Use the numbers given in each question.
- Tarrowfield has 900 hydrants, and maintaining one costs the department $120 a year. What does the department spend on hydrant maintenance in a year?
- The department spreads that yearly hydrant cost evenly across its 5,000 water accounts. What is the yearly hydrant cost per account?
- What is that cost per account per month?
- Firefighters drew water from Tarrowfield's hydrants 40 times last year. Using the yearly hydrant cost from question 1, what was the cost per use?
- A warehouse on the edge of Tarrowfield needs a larger main so that enough water reaches its sprinklers. The larger main costs $260,000, while the main the town would otherwise build costs $180,000. How much more does the larger main cost?
- What percent more is the larger main than the smaller one? Round to the nearest whole percent.
- The council proposes that the warehouse pay the extra cost over 10 years in equal yearly payments. What is each yearly payment?
- Most Tarrowfield households never have a fire. Explain why they still pay for hydrants every month.
- Give one reason the warehouse should pay the extra cost of the larger main.
- Give one reason the whole town should share that cost instead.
- Tarrowfield could pay for hydrants out of property taxes rather than water bills. Name one group that would pay more under a property tax, and explain 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
Answer: $108,000.
900 hydrants times $120 each equals $108,000 a year.Answer: $21.60.
$108,000 divided by 5,000 accounts equals $21.60 per account per year.Answer: $1.80.
$21.60 divided by 12 months equals $1.80 per account per month.Answer: $2,700.
$108,000 divided by 40 uses equals $2,700 per use. This figure is high because the cost comes from owning and maintaining hydrants, not from using them.Answer: $80,000.
$260,000 minus $180,000 equals $80,000 more for the larger main.Answer: 44 percent.
$80,000 divided by $180,000 equals about 0.444, which rounds to 44 percent more than the smaller main.Answer: $8,000.
$80,000 divided by 10 years equals $8,000 a year.Answer: Because hydrants have to exist and work before a fire starts, and nobody knows in advance whose house will need one. Households are paying for the protection being available, not for water they draw. Accept any answer that separates the cost of readiness from the cost of use.
Answer: Answers will vary. Reasonable answers note that the extra $80,000 exists only because of the warehouse's sprinklers, that the warehouse gains the benefit of insurable fire protection, or that charging the cost to the customer who causes it keeps other bills lower.
Answer: Answers will vary. Reasonable answers note that a fire at the warehouse could spread to nearby buildings, that the larger main also improves flow for neighbors, or that a town wanting the jobs the warehouse brings may decide the cost is a fair price.
Answer: Answers will vary. Reasonable answers name owners of high-value property, such as businesses or large homes, and explain that a property tax charges by assessed value rather than by account, so those owners would pay more than they do under a flat charge on the water bill. Accept the reverse point about renters, who pay property tax indirectly through rent.
Differentiation
Support
Provide a handout with the operation named beside each of items 1 through 7, such as "multiply" beside item 1 and "divide by 12" beside item 3, and allow calculators throughout. Give students a filled-in reference box listing the four fictional quantities they need most, which are 900 hydrants, $120 per hydrant per year, 5,000 accounts, and 40 uses last year.
Extension
Ask students to build a small table showing what the monthly hydrant charge per account would be if the fictional town had 3,000 accounts, 5,000 accounts, or 8,000 accounts, holding the $108,000 yearly cost constant. They should then write two sentences explaining what the table shows about how the number of accounts sharing a fixed cost affects each account's charge.
ELL supports
Pre-teach "hydrant," "main," "account," and "fire flow" with a labeled street drawing showing a hydrant, a small pipe, and a larger pipe. Provide a bilingual glossary card for those four terms. Allow items 8 through 11 to be answered in short phrases, and offer the frames "Households pay because ___" and "The warehouse should pay because ___."
Extensions
Have students look up whether their own water bill shows a separate fire protection charge, either on a family bill or on the sample bill many utilities post online. They can then compare the charge they find with the $1.80 a month the fictional Tarrowfield accounts pay and write one sentence about why the two figures might differ.