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Worksheet Grade 6 Careers & CTE

Brindle Creek Sampling Technician: Reading Test Results

A grade 6 careers worksheet where students act as a water sampling technician, comparing turbidity, lead, and PFAS readings to real water limits and finding percents.

Objectives

  1. Students will compare water-test readings to legal limits for turbidity, lead, and PFAS.
  2. Students will calculate the percent of samples that met a limit.

Vocabulary

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: sampling technician, parts per billion, compliance

Teacher overview

A sampling technician collects water from the plant and from homes, runs tests, and checks each result against a legal limit. This worksheet gives students a technician's sample log for a fictional town and has them decide which readings passed and which crossed a limit. The scenario uses three real limits: a turbidity target of 0.3 NTU, a lead action level of 15 ppb, and a limit of 4.0 ppt each for two PFAS chemicals, PFOA and PFOS. Students also find percents, a grade 6 ratio skill that technicians use when they summarize results.

Brindle Creek Sampling Technician: Reading Test Results — Grade 6 Careers & CTE
Name: ____________________________ Date: ______________

Student Worksheet

You are a sampling technician for the town of Brindle Creek, working for the Brindle Creek Water Department. Use these limits: finished-water turbidity should be 0.3 NTU or lower and must never go above 1 NTU; the lead action level is 15 ppb today and drops to 10 ppb in 2027; the PFAS limit, which water systems must meet by April 2029, is 4.0 ppt each for two chemicals, PFOA and PFOS. The lead action level is not a safe level. It is the point at which the water system must take extra steps, and EPA's health goal for lead is zero. Show your work.

  1. The finished-water turbidity readings for five days were 0.10, 0.12, 0.09, 0.35, and 0.11 NTU. The daily target is 0.3 NTU or lower. On how many of the five days did the reading meet the target?
  2. What percent of the five days met the 0.3 NTU target?
  3. The highest reading of the week was 0.35 NTU. The rule says finished water must never go above 1 NTU. Did that reading break the 1 NTU rule? Explain your answer.
  4. Nadia tested 20 homes for lead. Two homes were at or above the 15 ppb action level. How many homes were below the action level?
  5. What percent of the 20 homes were below the 15 ppb action level?
  6. A home measured 12 ppb of lead. Is that home below the action level today? Will it still be below the action level in 2027, when the level drops to 10 ppb?
  7. A well was tested for PFAS. PFOA measured 3.2 ppt and PFOS measured 4.6 ppt. The limit is 4.0 ppt for each. Which reading, if either, is above its limit?
  8. The 4.6 ppt reading is above the 4.0 ppt limit. How far above the limit is it?
  9. A technician reports to the utility whenever a sample crosses a limit. Explain why careful, accurate records matter for keeping the town's water safe.

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: 4 days.
    The readings 0.10, 0.12, 0.09, and 0.11 are all at or below 0.3 NTU; only 0.35 is above it, so 4 of the 5 days met the target.
  2. Answer: 80 percent.
    4 days out of 5 met the target. 4 / 5 = 0.80, or 80 percent.
  3. Answer: No.
    The 0.35 NTU reading is below the 1 NTU ceiling, so it did not break the never-above-1 rule, though it did miss the lower 0.3 NTU daily target for that day.
  4. Answer: 18 homes.
    20 homes tested minus the 2 homes at or above the action level = 18 homes below it.
  5. Answer: 90 percent.
    18 of 20 homes were below the action level. 18 / 20 = 0.90, or 90 percent.
  6. Answer: Below today, but not in 2027.
    12 ppb is below today's 15 ppb action level. In 2027 the level drops to 10 ppb, and 12 is above 10, so the same home would be over the action level then. Being below the action level does not make lead safe.
  7. Answer: The 4.6 ppt reading is above the limit.
    4.6 ppt is greater than the 4.0 ppt limit, so PFOS is over. The 3.2 ppt PFOA reading is below 4.0, so it is within the limit.
  8. Answer: 0.6 ppt above.
    4.6 ppt minus the 4.0 ppt limit equals 0.6 ppt above the limit.
  9. Answer: Accurate records prove the water met the law.
    A technician's records are the utility's evidence that each limit was checked and met; if a reading crosses a limit, the record is what triggers a fix, and a missed or sloppy record could let unsafe water go unnoticed.

Differentiation

Support

Give these students a number line for each limit (turbidity, lead, PFAS) with the limit marked, so they can place each reading and see at a glance whether it is above or below before answering. Allow a calculator for the percent items.

Extension

Ask students to design a new set of five daily turbidity readings of their own that would make exactly 60 percent of the days meet the 0.3 NTU target, and to show why their numbers give that percent.

ELL supports

Pre-teach "sampling technician," "action level," "parts per billion," and "compliance" with a labeled sample bottle and a simple above-or-below chart. Allow items 3, 6, 7, and 9 to be answered with short phrases plus the key number.