Quiz & test questions Grade 7 Social Studies & Civics
Grendon Buys Water From Kilbourne: A Grade 7 Quiz
A 27-point grade 7 quiz on a fictional town choosing between buying treated water from a neighbor and building its own plant, with percent and cost items.
Objectives
- Students will calculate a town's yearly cost under two competing water supply plans.
- Students will express the difference between two plans as a percent of the larger one.
- Students will identify a risk and a benefit of depending on a neighboring city for water.
Vocabulary
Key words: wholesale rate, pipeline, capital cost, operating cost, contract
Teacher overview
A small town whose wells are failing usually has two realistic choices, which are to build and own a treatment plant or to buy treated water from a larger neighbor under a long contract. This 27-point quiz sets that decision in a fictional town and mixes one multiple-choice item, eight computation items, and one short-answer item. Students price both plans, convert the gap between them into a percent, and then test what happens when the neighboring city raises its rate.
Assessment
Grendon is a fictional town with 3,000 households. Its two wells are failing, and the town must choose one of two plans. Under the contract plan, Grendon signs a 20-year agreement to buy treated water from the city of Kilbourne and builds a pipeline to carry it. Under the plant plan, Grendon builds and runs its own treatment plant. Show your work.
(2 points) Which statement best describes what Grendon buys under the contract plan?
- A) The right to pump water from Kilbourne's wells
- B) Treated drinking water delivered through a pipeline
- C) Part ownership of Kilbourne's treatment plant
- D) A seat on Kilbourne's city council
(3 points) Grendon would buy 90 million gallons a year at a wholesale rate of $2.40 for every 1,000 gallons. What is the yearly cost of the water itself?
(3 points) The pipeline would cost $3,600,000, paid off in equal yearly amounts over 20 years. What is the yearly pipeline payment?
(2 points) Add your answers from items 2 and 3. What is Grendon's total yearly cost under the contract plan?
(3 points) Grendon has 3,000 households. Using your answer from item 4, what is the yearly cost for each household under the contract plan?
(3 points) Under the plant plan, the treatment plant would cost $6,000,000, paid off in equal yearly amounts over 20 years, plus $150,000 a year to operate. What is the total yearly cost of the plant plan?
(3 points) Using your answer from item 6, what is the yearly cost for each household under the plant plan?
(3 points) Find the difference between the two yearly totals, then express that difference as a percent of the plant plan's total. Round to the nearest whole percent.
(3 points) Suppose Kilbourne raises its wholesale rate by 10 percent, from $2.40 to $2.64 for every 1,000 gallons. What would Grendon's total yearly cost under the contract plan become?
(2 points) Name one risk Grendon takes on by depending on Kilbourne for its water, and one benefit it gains.
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: B, treated drinking water delivered through a pipeline.
The contract plan buys finished water that Kilbourne has already treated. Choice A describes a groundwater right, choice C describes an ownership share, and choice D describes a governing role, none of which a purchase contract provides.Answer: $216,000.
90 million gallons is 90,000 units of 1,000 gallons. 90,000 times $2.40 is $216,000 a year.Answer: $180,000.
$3,600,000 divided by 20 years is $180,000 each year.Answer: $396,000.
$216,000 for the water plus $180,000 for the pipeline is $396,000 a year.Answer: $132.
$396,000 divided by 3,000 households is $132 for each household each year.Answer: $450,000.
$6,000,000 divided by 20 years is $300,000 a year to pay for the plant. Adding the $150,000 yearly operating cost gives $450,000.Answer: $150.
$450,000 divided by 3,000 households is $150 for each household each year.Answer: 12 percent.
$450,000 minus $396,000 is $54,000. $54,000 divided by $450,000 is 0.12, which is 12 percent.Answer: $417,600.
90,000 units times $2.64 is $237,600 for the water. Adding the unchanged $180,000 pipeline payment gives $417,600.Answer: Accept one risk and one benefit.
Reasonable risks include a rate increase Grendon cannot vote on, a contract that runs 20 years, and having no water source of its own if Kilbourne's supply is interrupted. Reasonable benefits include a lower yearly cost, no plant to staff or repair, and no responsibility for meeting treatment standards directly. Full credit requires one of each, stated in a complete sentence.
Differentiation
Support (below grade level)
Give these students the conversion in item 2 already set up as 90,000 units of 1,000 gallons, and provide a two-column worksheet for the fictional town that labels one column "contract plan" and the other "plant plan" so totals stay separated. Allow calculators on every item.
Extension (above grade level)
Ask students to find the wholesale rate at which the contract plan and the plant plan would cost the fictional town exactly the same each year, show the reasoning that produced it, and explain what that number tells a town negotiating a 20-year agreement.
ELL supports
Pre-teach "wholesale rate," "pipeline," and "operating cost" with a simple diagram showing one city plant, one pipeline, and one town. Provide a labeled table of the given figures separated by plan, and allow item 10 to be answered with two short sentences using a provided frame.