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Lesson plan Grade 6 Social Studies & Civics

Harnbeck's Lead Service Lines: Which Blocks Go First?

A grade 6 civics lesson where students find the percent of lead service lines in four neighborhoods and rank them for a town's replacement budget.

Objectives

  1. Students will calculate the percent of service lines that are lead in each of four neighborhoods.
  2. Students will use a per-line replacement cost to find how many lines a fixed budget can pay for.
  3. Students will defend a replacement order using both the percent data and a stated public-health reason.

Vocabulary

Service line
A service line is the small pipe that connects the water main under the street to the plumbing inside one home or building. It is the last leg of the trip water makes to your tap.
Lead (Pb)
A soft gray metal that is poisonous, especially for children. It can get into drinking water from old pipes and plumbing, so utilities work hard to control it.
Action level
A trigger number in lead and copper testing. If too many homes test above this level, the utility must take steps like improving treatment and telling the public.

Also: percent, capital budget, priority

Teacher overview

A federal rule now requires water systems to replace nearly all of their lead service lines within ten years, and EPA estimates that about 4 million of those lines are still in the ground nationwide. That November 2025 estimate is built from the service line inventories utilities reported, and it replaced an older estimate of about 9 million. Crews cannot replace every block at once, so councils have to decide which streets go first. This lesson puts that decision in front of students using the fictional town of Harnbeck, where four neighborhoods have very different shares of lead pipe and the town has money for only part of the work. One misconception worth addressing directly is the belief that lead gets into tap water at the reservoir or the treatment plant; in most cases the lead comes from the service line and the household plumbing between the water main and the faucet, which is why replacement is done street by street rather than at the plant.

Procedure

Hook (5 min): Project the four Harnbeck neighborhood names with their raw counts of lead lines only: Ivywell 120, Pellwood 100, Delmoor 75, Tilbury 90. Ask which neighborhood looks worst. Take a show of hands, record the vote, and tell students the counts alone are not enough information to answer.

Background on the rule (10 min): Explain that a service line is the small pipe that runs from the water main under the street into one building. Tell students that the federal lead action level is 15 parts per billion and drops to 10 parts per billion in 2027, and that the same rule requires systems to replace nearly all lead service lines within ten years. Name the source: the EPA Lead and Copper Rule Improvements. Clarify where the lead comes from, correcting the plant-water misconception named in the overview.

Modeling the percent (8 min): Reveal that the neighborhoods are different sizes. In the town of Harnbeck, Ivywell has 400 service lines in all and 120 of them are lead. Model the calculation on the board: 120 divided by 400 equals 0.30, which is 30 percent. Then model the budget arithmetic once, showing that a town paying $6,000 for one line can pay for two lines with $12,000.

Independent work (17 min): Students complete the eight questions on the student handout. Circulate and check that students are dividing the lead count by the neighborhood total rather than by the town total.

Ranking discussion (7 min): Groups post a replacement order for the four neighborhoods on chart paper and give one reason each. Push the discussion past the percents by asking two questions: does the neighborhood with the highest percent also have the most families waiting, and should an elementary school or a childcare center on a block change the order?

Exit ticket (3 min): Each student writes one sentence naming the neighborhood they would replace first and the single piece of evidence that most supports the choice. There is no one correct order, so score for whether the sentence names real evidence from the handout rather than a preference.

Harnbeck's Lead Service Lines: Which Blocks Go First? — Grade 6 Social Studies & Civics
Name: ____________________________ Date: ______________

Student Handout

The town of Harnbeck is replacing its lead service lines. A service line is the pipe that carries water from the main under the street into one building. The table shows what the town's crews found.

Neighborhood Service lines in all Lead service lines
Ivywell 400 120
Pellwood 250 100
Delmoor 500 75
Tilbury 200 90

Show your work for each question.

  1. Ivywell has 400 service lines, and 120 of them are lead. What percent of Ivywell's lines are lead?
  2. Pellwood has 250 service lines, and 100 of them are lead. What percent of Pellwood's lines are lead?
  3. Delmoor has 500 service lines, and 75 of them are lead. What percent of Delmoor's lines are lead?
  4. Tilbury has 200 service lines, and 90 of them are lead. What percent of Tilbury's lines are lead?
  5. Harnbeck's crews counted 120 lead lines in Ivywell, 100 in Pellwood, 75 in Delmoor, and 90 in Tilbury. How many lead service lines did the crews count in all?
  6. Harnbeck pays $6,000 to replace one lead service line. What would it cost to replace all 100 of Pellwood's lead lines?
  7. Harnbeck has $1,200,000 to spend on this work next year, and each line costs $6,000. How many lead lines can the town replace next year?
  8. Harnbeck has 1,350 service lines in all, and 385 of them are lead. What percent of the town's service lines are lead? Round to the nearest tenth.

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: 30%. In the town of Harnbeck, 120 divided by 400 equals 0.30, and 0.30 written as a percent is 30 percent.
  2. Answer: 40%. Here 100 divided by 250 equals 0.40, which is 40 percent.
  3. Answer: 15%. Here 75 divided by 500 equals 0.15, which is 15 percent.
  4. Answer: 45%. Here 90 divided by 200 equals 0.45, which is 45 percent. Tilbury has the highest share even though Ivywell has more lead lines.
  5. Answer: 385 lead service lines. Adding 120 plus 100 plus 75 plus 90 gives 385.
  6. Answer: $600,000. At $6,000 for each line, 100 lines cost 100 times $6,000, which is $600,000.
  7. Answer: 200 lines. Dividing $1,200,000 by $6,000 for each line gives 200 lines, which is a little more than half of the 385 lead lines in the town.
  8. Answer: 28.5%. Dividing 385 by 1,350 gives 0.285185, and rounded to the nearest tenth that is 28.5 percent. Accept 28.5 percent as long as the division is shown.

Differentiation

Support

Give these students a partly finished table with the first division already set up as 120 divided by 400, and let them use a calculator for every division. Provide a percent strip marked at 10, 25, 50, and 75 percent so they can check whether an answer is reasonable before writing it down. For questions 6 and 7, remind them that one asks them to multiply and the other asks them to divide.

Extension

Ask students to work out what share of all the lead lines in Harnbeck sits in a single neighborhood, then argue whether the town should rank neighborhoods by the percent of lines that are lead or by the raw number of families served. Have them write two sentences explaining which measure they would put in front of the council and why the two measures disagree here.

ELL supports

Pre-teach "service line," "lead," "replace," and "budget" with a simple cross-section drawing of a street showing the main, the service line, and a house. Provide sentence frames for the ranking discussion: "I would replace ___ first because ___ percent of its lines are lead." Allow the exit ticket to be answered in a short phrase or in a student's first language with a labeled drawing.

Extensions

Invite a staff member from the local water department or public works office to explain how the community actually finds its lead lines, since many systems are still working through old tap cards and paper records. Students can prepare three questions in advance, including one about how the department decides which street goes first and one about how residents are told what material their own service line is made of.