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Lesson plan Grade 9 Careers & CTE

Quarry Hill Morning Rounds: An Operator Reads the Daily Log

A 50-minute grade 9 careers lesson where students act as an operator trainee, converting a plant's flow and checking daily readings against real regulatory limits.

Objectives

  1. Students will convert a plant's flow between million gallons per day and gallons per minute using a stated conversion.
  2. Students will compare daily plant readings against real regulatory limits and decide whether an operator should act.

Vocabulary

Turbidity
Turbidity is a measure of how cloudy or murky water looks because of tiny particles floating in it. Clear water has low turbidity, and muddy water has high turbidity.
Chlorine residual
Chlorine residual is the small amount of chlorine still left in the water after it leaves the treatment plant. It keeps protecting the water from germs all the way to your faucet.
Flow rate
Flow rate measures how much water moves past a point in a certain amount of time, like gallons per minute through a garden hose. Bigger pipes and stronger pushes give bigger flow rates.

Also: daily log

Teacher overview

Every treatment plant keeps a daily log of readings, and the operator's first job each shift is to read that log and decide whether anything needs attention. This lesson puts students in the role of an operator trainee reading a plant's morning log. They convert the plant's flow to a per-minute rate and then check three readings against real limits: turbidity at or below 0.3 NTU, a chlorine residual inside the usual 0.2 to 2.0 mg/L range, and pressure in the normal band. A common student error is to compare a reading to a limit without checking the units first, so this lesson keeps units visible at every step.

Procedure

Hook (5 min): Ask students what could go wrong if no one checked a water plant's readings for a full day. Take a few answers, then explain that an operator's rounds catch small problems before they reach homes. Tell students they will read a realistic daily log for the fictional Quarry Hill plant.

Direct instruction (12 min): Project the day's numbers for Quarry Hill, a fictional plant treating 2.5 MGD (million gallons per day). Model Question 1 from the handout carefully, writing the units at each step: 2.5 MGD is a daily flow, and using the conversion that 1 MGD equals 694 gpm, 2.5 MGD is 2.5 times 694, or about 1,735 gpm. Then model one check that is not scored on the handout: the log shows turbidity of 0.28 NTU, and the limit is 0.3 NTU or below, so 0.28 is under the limit and no action is needed. Stress that the reading and the limit must share the same unit before comparing.

Guided practice (15 min): In pairs, students work Questions 2 through 4 on the handout using the same day's log. They confirm the chlorine residual of 0.9 mg/L sits inside the 0.2 to 2.0 mg/L range, they check a pressure reading of 62 psi against the normal 40 to 80 psi band, and they convert a second day's flow of 3.0 MGD to gpm. Circulate and confirm each pair writes units at every step.

Independent practice (13 min): Each student completes Questions 5 and 6 alone. In Question 5, the turbidity reads 0.45 NTU; students decide whether the operator must act and explain why. In Question 6, students convert a flow of 1.5 MGD to gpm and state the result to a sensible number of digits.

Closure and exit ticket (5 min): On an index card, each student answers Question 7: "A morning log shows turbidity of 0.5 NTU. Is that within the 0.3 NTU limit, and what should the operator do?" Collect the cards and check that students compare to the correct limit before deciding.

Quarry Hill Morning Rounds: An Operator Reads the Daily Log — Grade 9 Careers & CTE
Name: ____________________________ Date: ______________

Student Handout

Operator trainee daily log for the fictional Quarry Hill plant

You are the operator trainee on morning rounds. Use these reference values for every question below, and write the units at each step before you compare a reading to its limit.

  • Flow conversion: 1 MGD (million gallons per day) equals 694 gpm (gallons per minute).
  • Finished-water turbidity: the federal rule requires 0.3 NTU or below in at least 95 percent of monthly samples and never above 1 NTU, so an operator acts on any reading above 0.3 NTU.
  • Chlorine residual normal range: 0.2 to 2.0 mg/L.
  • Distribution pressure normal band: 40 to 80 psi.
  1. The plant is treating 2.5 MGD this morning. Convert that flow to gallons per minute (gpm).
  2. The log shows a chlorine residual of 0.9 mg/L. Is that reading inside the normal range, and does the operator need to act on it?
  3. The log shows a distribution pressure of 62 psi. Is that reading inside the normal band, and does the operator need to act on it?
  4. A second day's log shows a flow of 3.0 MGD. Convert that flow to gpm.
  5. On another morning the turbidity reads 0.45 NTU. Decide whether the operator must act, and explain why.
  6. Convert a flow of 1.5 MGD to gpm, and state the result to a sensible number of digits.
  7. Exit ticket: a morning log shows turbidity of 0.5 NTU. Is that within the 0.3 NTU limit, and what should the operator do?

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: about 1,735 gpm. 2.5 MGD times 694 gpm per MGD equals 1,735 gpm.
  2. Answer: within range. The residual of 0.9 mg/L falls between 0.2 and 2.0 mg/L, so no action is needed on that reading.
  3. Answer: within range. A pressure of 62 psi sits inside the normal 40 to 80 psi band, so it is acceptable.
  4. Answer: about 2,082 gpm. 3.0 MGD times 694 gpm per MGD equals 2,082 gpm.
  5. Answer: the operator must act. A turbidity of 0.45 NTU is above the 0.3 NTU level the rule requires in 95 percent of samples, so the operator should investigate the filters and adjust treatment, then re-check.
  6. Answer: about 1,041 gpm. 1.5 MGD times 694 gpm per MGD equals 1,041 gpm; reporting it as about 1,040 gpm is reasonable because 1.5 MGD is itself a rounded reading.
  7. Exit ticket answer: not within the limit; the operator should act. A turbidity of 0.5 NTU is above the 0.3 NTU level the rule requires in 95 percent of samples, so the operator investigates and corrects treatment before the water moves on.

Differentiation

Support

Give students a reference strip listing the three limits (turbidity 0.3 NTU or below, chlorine residual 0.2 to 2.0 mg/L, pressure 40 to 80 psi) and the conversion (1 MGD equals 694 gpm), so they can focus on comparing rather than recalling. Provide the first conversion already set up.

Extension

Ask students to write one sentence explaining why an operator reports a converted flow such as the one in Question 6 as a rounded value rather than to every digit, connecting the answer's precision to the precision of the input.

ELL supports

Pre-teach "daily log," "turbidity," "chlorine residual," and "flow rate" with a labeled picture and simple definitions. Provide a sentence frame for each check: "The reading is ___, the limit is ___, so the operator should ___."