Worksheet Grade 6 Science

Reading Alderfen's Water Quality Report: Numbers and Limits

A grade 6 science worksheet where students read a fictional town's yearly water quality table, compare each result to its legal limit, and subtract to find the margin.

Grade: Grade 6
Subject: Science
Material: Worksheet
Time: 35 min
Prep: No prep
Materials: None

Standards

RST.6-8.7 Common Core ELA

Integrate quantitative or technical information expressed in words in a text with a version of that information expressed visually (e.g., in a flowchart, diagram, model, graph, or table).

How this material aligns: Students integrate the words of each question with the quantitative data in Alderfen's report table, reading turbidity, chlorine, pH, and lead values against their limits in items 1 through 8.

All materials for RST.6-8.7 →

6.NS.B.3 Common Core Math

Fluently add, subtract, multiply, and divide multi-digit decimals using the standard algorithm for each operation.

How this material aligns: Items 2, 3, and 7 require students to subtract multi-digit decimals, such as 0.3 minus 0.08 and 4.0 minus 0.9, to find how far each result sits from its limit.

All materials for 6.NS.B.3 →

MS-ESS3-3 NGSS

Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment.

How this material aligns: Items 8, 9, and 10 have students explain what turbidity measures, why a utility monitors turbidity, chlorine, pH, and lead together rather than one alone, and why publishing the results helps the public, the reasoning about a monitoring method that this standard asks for.

All materials for MS-ESS3-3 →

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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 read values from a water quality report table and compare each one to its legal or target limit.
Students will subtract decimals to find how far a result sits below its limit.
Students will explain why a utility tests for several different measures instead of one.

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.
pH: pH is a number that tells whether water is acidic, like lemon juice, or basic, like baking soda mixed in water. Pure water sits in the middle of the scale at a pH of 7.
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.

Teacher overview

Every year, a water utility mails its customers a report that lists what is in the tap water. This worksheet uses the yearly report from the fictional town of Alderfen. Students read each measured result, compare it to the legal or target limit, and subtract to find the margin. The real limits come from federal drinking-water rules; Alderfen's own results are made up for this worksheet.

Reading Alderfen's Water Quality Report: Numbers and Limits — Grade 6 Science

Name: ____________________________ Date: ______________

Student Worksheet

The table below is the yearly water report for the fictional town of Alderfen. Use it to answer the questions.

Measure	Alderfen's result	Legal or target limit
Turbidity (cloudiness)	0.08 NTU	at or below 0.3 NTU
Chlorine left in the pipes	0.9 mg/L	at or below 4.0 mg/L
pH	7.4	between 6.5 and 8.5
Lead	3 ppb	action level 15 ppb, dropping to 10 ppb in 2027

Alderfen's turbidity result is 0.08 NTU. The limit is 0.3 NTU or lower. Is Alderfen's water at or below the turbidity limit?
How far below the 0.3 NTU turbidity limit is Alderfen's result of 0.08 NTU? Subtract to find out.
Alderfen's chlorine result is 0.9 mg/L. The highest amount allowed is 4.0 mg/L. How much lower than the top limit is Alderfen's chlorine?
Water systems usually keep chlorine between 0.2 and 2.0 mg/L in the pipes. Is Alderfen's 0.9 mg/L inside that usual range?
Alderfen's pH is 7.4. The target range is 6.5 to 8.5. Is the town's water inside the target range?
Alderfen's lead result is 3 ppb. The action level is 15 ppb now, and it will drop to 10 ppb in 2027. Will Alderfen still be below the action level after the 2027 change? Explain.
By how many ppb is Alderfen's lead result of 3 ppb below the new 2027 action level of 10 ppb?
A neighbor says a low turbidity number is a good sign. Explain what turbidity measures and why a low result is good news for the town.
Explain why a utility tests for several different things, such as turbidity, chlorine, pH, and lead, instead of just one.
The report is mailed to every home once a year. Give one reason it helps people to see these numbers for themselves.

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: Yes.
0.08 NTU is less than the 0.3 NTU limit, so the water meets the turbidity standard.
Answer: 0.22 NTU.
0.3 - 0.08 = 0.22, so the result is 0.22 NTU below the limit.
Answer: 3.1 mg/L.
4.0 - 0.9 = 3.1, so the chlorine is 3.1 mg/L below the top limit of 4.0 mg/L.
Answer: Yes.
0.9 mg/L falls between 0.2 and 2.0 mg/L, so it is inside the usual range for chlorine in the pipes.
Answer: Yes.
7.4 falls between 6.5 and 8.5, so the pH is inside the target range.
Answer: Yes.
Alderfen's lead is 3 ppb, and 3 is still less than the new 10 ppb action level, so the town stays below the action level after the 2027 change. The action level tells the utility when it must act. It is not a safe level, because EPA's health goal for lead is zero.
Answer: 7 ppb.
10 - 3 = 7, so the lead result is 7 ppb below the new action level.
Answer: Turbidity measures how cloudy the water is, and a low result means the water is clear.
Clear water is easier to disinfect and is a sign that the filters are working. Accept any answer that says turbidity is cloudiness and low means clearer, cleaner-looking water.
Answer: One test cannot catch every problem, so the utility checks several measures.
Turbidity, chlorine, pH, and lead each show a different thing about the water, so testing all of them gives a fuller picture of safety. Accept any answer with this idea.
Answer: Seeing the numbers lets people check that the water meets the limits and ask questions.
Accept any reasonable answer, such as building trust, spotting a problem early, or helping families make choices.

Differentiation

Support

Highlight the two numbers each question needs before students subtract, and give a number line for items 2, 3, and 7 so students can see the gap between the result and the limit. Let students answer items 1, 4, and 5 by circling "yes" or "no."

Extension

Ask students to write a short note to Alderfen's customers that explains, in plain words, whether the water met its limits this year and which result had the most room to spare. Have them support the claim with two numbers from the table.

ELL supports

Pre-teach "turbidity," "chlorine," "pH," "lead," and "limit" with a simple picture for each. Provide sentence frames such as "Alderfen's result is ___, and the limit is ___, so the water is ___ the limit."