Worksheet Grade 7 Math

Kestrel Hollow's Lead Service Lines: A Percent Worksheet

A grade 7 percent worksheet set in the fictional town of Kestrel Hollow, where students find lead-line counts, replacement costs, and percent changes.

Grade: Grade 7
Subject: Math
Material: Worksheet
Time: 40 min
Prep: No prep
Materials: Calculator (optional)

Standards

7.RP.A.3 Common Core Math

Use proportional relationships to solve multistep ratio and percent problems. Examples: simple interest, tax, markups and markdowns, gratuities and commissions, fees, percent increase and decrease, percent error.

How this material aligns: Items 4 through 10 use proportional reasoning for percent of a total, percent increase, percent decrease, and a percent-of fee, the exact multistep percent work this standard names.

All materials for 7.RP.A.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 calculate what percent one quantity is of a total in a water-system context.
Students will find percent increase and percent decrease from before-and-after values.

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: percent decrease, percent increase

Teacher overview

The fictional town of Kestrel Hollow is replacing the lead service lines that still carry water to some homes. This worksheet turns that project into percent practice: what share of the pipes are lead, how much a home's lead reading dropped after treatment, and how much a year of work costs the town. The lead action level is 15 ppb today and drops to 10 ppb in 2027, so a few items ask students to compare a reading against both levels. A useful teaching note: many students confuse the base of a percent decrease, dividing the change by the new value instead of the original, so watch item 5 and item 6 closely and remind them the original reading is always the denominator.

Kestrel Hollow's Lead Service Lines: A Percent Worksheet — Grade 7 Math

Name: ____________________________ Date: ______________

Student Worksheet

Kestrel Hollow is a fictional town. Its water utility is replacing old lead service lines. A service line is the pipe that carries water into one home. The lead action level is 15 ppb. In 2027 the action level drops to 10 ppb. Use these facts for every question:

The town has 4,000 service lines in all.
900 of those lines are lead.
Last year the utility replaced 180 lead lines.
This year it plans to replace 225 lead lines.
Each replacement costs $6,000.
A state grant pays 65% of the cost.

What percent of the town's 4,000 service lines are lead? Round to the nearest tenth of a percent.
Last year the utility replaced 180 of the 900 lead lines. What percent of the lead lines is that?
How many lead lines are still in the ground after last year's work?
The utility tested 200 homes. In 24 of them the lead reading was above 15 ppb. What percent of the tested homes were above the action level?
One home read 25 ppb. After the utility added corrosion control, it read 18 ppb. Find the percent decrease. Round to the nearest whole percent.
A second home dropped from 20 ppb to 8 ppb. Find the percent decrease.
Is that second home's reading below the 2027 action level of 10 ppb? Explain how you know.
This year's plan of 225 replacements is up from 180 last year. Find the percent increase.
Each replacement costs $6,000. What is the total cost of all 225 replacements this year?
The state grant pays 65% of that total. How many dollars does the town itself pay?

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: 22.5%.
900 ÷ 4,000 = 0.225, which is 22.5%.
Answer: 20%.
180 ÷ 900 = 0.2, which is 20%.
Answer: 720 lines.
900 − 180 = 720 lead lines remain.
Answer: 12%.
24 ÷ 200 = 0.12, which is 12%.
Answer: 28%.
The change is 25 − 18 = 7. Divide by the original: 7 ÷ 25 = 0.28, which is 28%.
Answer: 60%.
The change is 20 − 8 = 12. Divide by the original: 12 ÷ 20 = 0.6, which is 60%.
Answer: Yes.
8 ppb is below 10 ppb. The action level is a trigger for utility action, not a safe level. EPA's health goal for lead is zero.
Answer: 25%.
The change is 225 − 180 = 45. Divide by the original: 45 ÷ 180 = 0.25, which is 25%.
Answer: $1,350,000.
225 × $6,000 = $1,350,000.
Answer: $472,500.
The grant covers 65%, so the town pays the other 35%. 0.35 × $1,350,000 = $472,500.

Differentiation

Support

Give students a printed reference card with two labeled rules: "part ÷ whole = percent of the whole" and "change ÷ original = percent change." Work item 1 aloud as a model before releasing the rest, and let students use a calculator so the reasoning, not the arithmetic, is the focus.

Extension

Ask students to find the year the town will finish, assuming it replaces 225 lines each year starting from the 720 that remained after last year. Then have them explain why replacing a fixed number each year does not produce a fixed percent each year.

ELL supports

Pre-teach "increase," "decrease," and "action level" with a simple before-and-after picture of a pipe and a gauge. Provide the sentence frame "The reading went from ___ to ___, a decrease of ___ percent" for items 5 and 6 so students can show their reasoning in words.

Extensions

Invite students to look up whether your own state or water utility publishes a lead service line replacement plan, using only figures the utility itself reports. Compare the share of lines still made of lead in that real plan with the 22.5 percent share in Kestrel Hollow, and discuss why some towns have far more lead lines than others.