Worksheet Grade 6 Social Studies & Civics

Reading Thornby's Yearly Water Quality Report

A grade 6 civics worksheet where students read a fictional town's annual water quality report, compare test results to legal limits, and find one result as a percent.

Grade: Grade 6
Subject: Social Studies & Civics
Material: Worksheet
Time: 30 min
Prep: No prep
Materials: None

Standards

RI.6.1 Common Core ELA

Cite textual evidence to support analysis of what the text says explicitly as well as inferences drawn from the text.

How this material aligns: Students cite specific numbers from the report table to support their answers about which results stay within the legal limits.

All materials for RI.6.1 →

6.RP.A.3 Common Core Math

Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations, including finding a percent of a quantity and converting measurement units.

How this material aligns: Item 7 asks students to express a lead result as a percent of the action level, using the ratio and percent reasoning this standard requires.

All materials for 6.RP.A.3 →

D2.Civ.13.6-8 C3 Framework

Analyze the purposes, implementation, and consequences of public policies in multiple settings.

How this material aligns: Students examine why towns must publish a yearly water report and what an action level requires, analyzing the purpose of this public health policy.

All materials for D2.Civ.13.6-8 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-23.

Objectives

Students will compare drinking water test results to their legal limits using a data table.
Students will express a test result as a percent of its limit and explain why towns publish the report.

Vocabulary

Contaminant: A contaminant is anything in water that should not be there, whether it is a germ, a chemical, or too much of a natural mineral, that could make the water unsafe or unpleasant to use. Treatment plants are built specifically to find and remove contaminants before water reaches the tap.
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.
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: residual, limit

Teacher overview

Every year, a water utility must mail its customers a report on what is in their tap water. This worksheet gives students a short version of that report for a fictional town. Students compare each test result to its legal limit, decide whether the water is within the rules, and turn one result into a percent. The task builds a real civic skill: reading the water report that arrives in a family's mailbox.

Reading Thornby's Yearly Water Quality Report — Grade 6 Social Studies & Civics

Name: ____________________________ Date: ______________

Student Worksheet

The fictional town of Thornby sent this water report to every home. The table shows four test results and the legal limit for each one. Each result should stay at or below its limit. Chlorine is different: a small amount must stay in the pipes to keep killing germs. Use the table to answer the questions.

Test	Thornby's result	Legal limit
Turbidity (cloudiness)	0.08 NTU	0.3 NTU
Chlorine left in water	0.9 mg/L	4.0 mg/L, at most
Lead	3 ppb	15 ppb action level
PFOA (a "forever chemical")	2.1 ppt	4.0 ppt

Water systems must meet the PFOA limit by April 2029. In May 2026, EPA proposed letting some systems that qualify ask for two more years, to April 2031. The 4.0 ppt limit would stay the same, and the plan was not final as of September 2026.

What was Thornby's turbidity result?
The turbidity limit is 0.3 NTU. Is Thornby's result under the limit? By how many NTU?
What was Thornby's chlorine result? Is it under the 4.0 mg/L top limit?
Thornby's lead result is 3 ppb. The action level is 15 ppb. Is the result under the action level, and by how many ppb?
In 2027 the lead action level drops to 10 ppb. Would Thornby's 3 ppb result still be under the new, lower limit?
Thornby's PFOA result is 2.1 ppt. The limit is 4.0 ppt. Is the result under the limit, and by how much?
Thornby's lead result of 3 ppb is what percent of the 15 ppb action level?
Look at how close each result is to its own limit. Which test result is the closest to its limit? Explain using the table.
Explain in one or two sentences why a town mails this report to every home each year.
The lead limit is called an "action level." Explain what a town must start doing if a result goes above an action level.

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: 0.08 NTU. The table lists Thornby's turbidity result as 0.08 NTU in the top row.
Answer: Yes, by 0.22 NTU. The result 0.08 is under the 0.3 limit, and 0.3 minus 0.08 equals 0.22 NTU.
Answer: 0.9 mg/L, yes. The chlorine result of 0.9 mg/L is well under the 4.0 mg/L top limit.
Answer: Under, by 12 ppb. The result 3 ppb is under the 15 ppb action level, and 15 minus 3 equals 12 ppb.
Answer: Yes, by 7 ppb. The 3 ppb result is still under the new 10 ppb action level, since 10 minus 3 equals 7 ppb.
Answer: Under, by 1.9 ppt. The result 2.1 ppt is under the 4.0 ppt limit, and 4.0 minus 2.1 equals 1.9 ppt.
Answer: 20%. The lead result 3 ppb divided by the 15 ppb action level is 3 divided by 15, which equals 0.20, or 20 percent.
Answer: PFOA. The PFOA result 2.1 ppt is a little over half of its 4.0 ppt limit, while every other result is well under half of its limit, so PFOA is closest to its line.
Answer: A town mails the report so residents can see for themselves what is in the water and check that the results stay within the legal limits, which builds public trust.
Answer: If a result goes above an action level, the town must take steps to lower it, such as treating the water differently and replacing old pipes, and it must tell the public.

Differentiation

Support

Give these students a copy of the table with a blank "Under the limit?" column they can check off before answering. Provide the subtraction for item 2 already set up, and allow a calculator for the percent in item 7.

Extension

Ask students to write a short note a resident could send the town asking why the PFOA result is the closest to its limit, and what the town plans to do to keep it from rising. Their note should quote at least two numbers from the table.

ELL supports

Pre-teach "contaminant," "limit," "action level," and "residual" with a simple picture of a measuring line and a mark below it. Provide a sentence frame: "The result ___ is under the limit ___ by ___." Allow students to answer items 9 and 10 with short phrases.