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Lesson plan Grade 10 Social Studies & Civics

Staffing the Thornwick Plant Before the Retirements

A grade 10 lesson on a fictional water authority's staffing gap, where students compute shift coverage and vacancy rates and weigh overtime against hiring.

Objectives

  1. Students will calculate shift coverage, vacancy rate, and retirement exposure for a utility workforce.
  2. Students will compare the annual cost of sustained overtime with the cost of hiring additional operators.
  3. Students will rank three staffing policies and defend the ranking using cost and licensing evidence.

Vocabulary

Apprenticeship
A way to learn a skilled job by working alongside experienced workers while getting paid. Water utilities use apprenticeships to train new operators and technicians.

Also: licensed operator, certification class, vacancy rate, retirement eligibility, overtime, succession planning

Teacher overview

Every community drinking water system must be run by state-licensed operators, and roughly one-third of the water workforce becomes retirement-eligible within the next decade. Federal labor projections put about 10,000 operator openings a year, on average, from 2025 to 2035, even though total operator employment is projected to decline 6 percent; all of those openings come from replacing operators who retire or move to other occupations rather than from growth in the number of plants. This lesson gives students the staffing books of a fictional utility, the Thornwick Regional Water Authority, and asks them to do the arithmetic a general manager does before a budget hearing. The misconception worth correcting directly is the common student assumption that a modern treatment plant runs itself under automatic controls and needs staff only when something breaks; many states in fact require a licensed operator on duty whenever a treatment plant like Thornwick's is producing water, which is why a vacancy turns into overtime rather than into savings.

Procedure

Framing the labor market (8 min): Post two figures and ask students what they predict from them: median pay for water and wastewater treatment plant and system operators was $60,020 a year in May 2025, according to the Bureau of Labor Statistics, and about 10,000 openings are projected each year, on average, from 2025 to 2035. Ask what kind of job market those two numbers together describe. Explain that operator work typically begins with a high school diploma, on-the-job training, and a state license earned by exam, with licenses issued in classes tied to plant size, while the same authority also employs engineers and hydrologists in roles that require four-year or graduate degrees. All of these are ordinary ways into the sector.

Reading the staffing table (10 min): Distribute the handout and read the fictional Thornwick scenario aloud. Have students underline every number before they calculate anything, and ask one student to state in plain words what the plant is required to do around the clock. Confirm that two licensed operators must be on duty for every shift.

Handout calculations (20 min): Students work questions 1 through 6 in pairs with calculators. Circulate and watch for the two predictable errors: multiplying shifts per day by operators without accounting for all seven days, and computing the vacancy rate against filled positions instead of budgeted positions.

Policy ranking (12 min): Post the three options the authority is considering: keep paying overtime, hire two operators at the median salary, or fund a two-year paid apprenticeship that produces licensed operators from within the community. Groups rank the three and write one sentence of justification per rank on chart paper. Require each group to cite at least one number from the handout.

Exit ticket (5 min): Students answer question 7 individually and hand it in. Scan for whether the comparison of the two annual costs is stated correctly before the class leaves. If more than a third of the exit tickets reverse the comparison, reteach question 5 at the start of the next period.

Staffing the Thornwick Plant Before the Retirements — Grade 10 Social Studies & Civics
Name: ____________________________ Date: ______________

Student Handout

The Thornwick Regional Water Authority (a fictional utility). Thornwick treats and delivers drinking water for a town of 61,000 people. The authority budgets 24 licensed operator positions and currently has 19 of them filled. Seven of the 19 operators now on staff will reach retirement eligibility within five years. The treatment plant runs continuously, in three 8-hour shifts a day, seven days a week, and two licensed operators must be on duty for every shift. Each operator works five 8-hour shifts a week. Thornwick's base operator wage is $32.00 an hour, and overtime is paid at 1.5 times that wage. The authority is now covering 60 overtime hours each week. Benefits cost the authority an additional 35 percent of an operator's salary.

  1. How many operator-shifts must Thornwick cover at the plant each week? Show the shifts per day, the days per week, and the operators per shift in your work.
  2. If each operator works five shifts a week, how many operators are needed to cover the plant schedule alone, not counting vacation, sick leave, or training? Round up to a whole operator.
  3. Five of Thornwick's 24 budgeted operator positions are unfilled. What is the vacancy rate, to the nearest tenth of a percent?
  4. Seven of the 19 operators now on staff reach retirement eligibility within five years. What percent of the current staff is that, to the nearest tenth of a percent?
  5. Thornwick pays 60 overtime hours a week at 1.5 times its $32.00 base wage. What does that overtime cost the authority over a 52-week year?
  6. Federal wage data put median pay for water and wastewater treatment plant and system operators at $60,020 a year. If Thornwick hired two operators at that salary and paid benefits equal to 35 percent of salary, what would those two positions cost for one year?
  7. Compare your answers to questions 5 and 6. State which is the larger annual cost, and give one reason the authority might keep paying overtime anyway.

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: 42 operator-shifts per week. Three 8-hour shifts a day across seven days is 21 shifts, and two operators on each shift gives 21 times 2, or 42 operator-shifts.
  2. Answer: 9 operators. Dividing 42 operator-shifts by the five shifts each operator works gives 8.4, and a fraction of an operator cannot be scheduled, so the plant needs 9.
  3. Answer: 20.8 percent. Five unfilled positions divided by 24 budgeted positions is 0.2083, which rounds to 20.8 percent.
  4. Answer: 36.8 percent. Seven operators divided by the 19 now on staff is 0.3684, which rounds to 36.8 percent, close to the national pattern in which roughly one-third of the water workforce becomes retirement-eligible within a decade.
  5. Answer: $149,760 per year. The overtime wage is 1.5 times $32.00, or $48.00 an hour; 60 hours a week at $48.00 is $2,880 a week; and $2,880 across 52 weeks is $149,760.
  6. Answer: $162,054 per year. Benefits at 35 percent add $21,007 to a salary of $60,020, giving $81,027 for one position, and two positions cost 2 times $81,027, or $162,054.
  7. Answer: Hiring the two operators is the larger annual cost, by about $12,294. Accept any sound reason for continuing overtime, such as the months it takes to recruit and license a new operator, a shortage of certified applicants, a hiring freeze imposed by the board, or the fact that overtime can be cut in a bad revenue year while a salaried position cannot.

Differentiation

Support

Give students a partially completed calculation frame for questions 1, 5, and 6, with the operations labeled in order and the first product already filled in. Allow the vacancy and retirement percentages to be reported to the nearest whole percent rather than the nearest tenth.

Extension

Have students price the third option themselves. Ask them to write the assumptions a paid apprenticeship would need, such as a stipend, a supervising operator's time, and the number of months before the apprentice can sit for the license exam, and then explain which of those assumptions their estimate depends on most.

ELL supports

Pre-teach "shift," "vacancy," "overtime," and "retirement eligibility" with a simple weekly schedule grid showing three shifts a day and two operators in each block. Provide sentence frames for question 7, such as "The larger annual cost is ___ because ___" and "The authority might keep paying overtime because ___."