Quiz & test questions Grade 7 Engineering & Design
Tallowmere Orchard Pond Liner: Grade 7 Engineering Design Test
A 32-point grade 7 test where students size a fictional irrigation pond, compute seepage saved by two liners, and compare their yearly costs before recommending one.
Objectives
- Students will distinguish a design criterion from a design constraint in an irrigation project.
- Students will compute a pond volume and apply percent reductions to a daily seepage rate.
- Students will compare two design options on yearly cost and recommend one with evidence.
Vocabulary
Key words: seepage, liner, criterion, constraint, yearly cost
Teacher overview
This end-of-unit test is worth 32 points and covers the engineering design work of a grade 7 unit on water systems. It mixes two multiple-choice items, two written-response items, and eight computation items, all drawn from one scenario: a fictional fruit farm choosing a liner for its leaking irrigation pond. The seepage and cost items do not depend on the pond volume, so a student who misses the volume early can still earn full credit on everything that follows. The final item asks for a written recommendation supported by two numbers from earlier in the test, which is where the engineering reasoning is scored rather than the arithmetic.
Assessment
Read the scenario, then answer every item. Show your work on the computation items.
Tallowmere Orchard is a fictional fruit farm. Its irrigation pond is a rectangle 120 feet long, 60 feet wide, and 6 feet deep. The pond leaks through its sandy bottom at a rate of 2,400 gallons each day. The irrigation season lasts 150 days. One cubic foot of water holds 7.48 gallons. The farm is choosing between two liners. Liner A is packed clay. It costs $9,000, cuts seepage by 60 percent, and lasts 10 years. Liner B is a plastic sheet. It costs $21,000, cuts seepage by 95 percent, and lasts 20 years.
Which of these is a constraint on the liner project? (2 points)
- A. The pond must lose less water each day.
- B. The farm can spend no more than a set amount this year.
- C. The orchard needs water in July.
- D. The pond bottom is sandy.
Write one criterion the liner must meet. Your criterion must include a number or a measurable target. (2 points)
The pond is 120 feet long, 60 feet wide, and 6 feet deep. How many cubic feet does it hold? (3 points)
Using 7.48 gallons for every cubic foot, how many gallons does the pond hold? (3 points)
The pond leaks 2,400 gallons each day. How many gallons does it lose across the 150-day season? (2 points)
Liner A cuts seepage by 60 percent. How many gallons a day would Liner A save? (3 points)
With Liner A in place, how many gallons a day would the pond still lose? (2 points)
Liner B cuts seepage by 95 percent. How many gallons a day would Liner B save? (3 points)
Liner A costs $9,000 and lasts 10 years. What is its cost for each year? (3 points)
Liner B costs $21,000 and lasts 20 years. What is its cost for each year? (3 points)
A neighbor says the farm should just buy the cheaper liner. Which statement best explains why the farm compares cost for each year instead of purchase price? (2 points)
- A. Yearly cost is always smaller, so it looks better on paper.
- B. Purchase price is not real money until the liner is installed.
- C. The two liners last different numbers of years, so their prices are not comparable as they stand.
- D. Yearly cost includes the water saved, and purchase price does not.
Recommend Liner A or Liner B to the farm. Support your choice with two numbers from this test, and name one thing you would still want to know before ordering. (4 points)
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.
A constraint is a limit the design must stay inside. A spending cap is such a limit. Choice A is a criterion, since it states what the design must achieve. Choice C describes a need, and choice D is a site condition that explains the problem rather than bounding the solution.Answer: Accept any measurable criterion.
Correct answers name a target with a number attached, such as "the pond must lose no more than 500 gallons a day" or "the liner must hold water for at least 15 years." Award full credit only when a number or a measurable target is present. A bare statement such as "the liner should work well" earns one point at most.Answer: 43,200 cubic feet.
120 feet x 60 feet x 6 feet = 43,200 cubic feet.Answer: 323,136 gallons.
43,200 cubic feet x 7.48 gallons per cubic foot = 323,136 gallons.Answer: 360,000 gallons.
2,400 gallons per day x 150 days = 360,000 gallons lost across the season.Answer: 1,440 gallons per day.
60 percent of 2,400 gallons = 0.60 x 2,400 = 1,440 gallons saved each day.Answer: 960 gallons per day.
2,400 gallons leaking minus 1,440 gallons saved = 960 gallons still lost each day.Answer: 2,280 gallons per day.
95 percent of 2,400 gallons = 0.95 x 2,400 = 2,280 gallons saved each day, leaving 120 gallons of daily loss.Answer: 900 dollars per year.
$9,000 divided by 10 years = $900 for each year of service.Answer: 1,050 dollars per year.
$21,000 divided by 20 years = $1,050 for each year of service.Answer: C.
The liners last 10 and 20 years, so comparing the two purchase prices compares unlike things. Dividing each price by its service life puts both on the same yearly footing. Choice A is not always true, choice B misstates how purchases work, and choice D is wrong because the yearly cost figures here contain no water value at all.Answer: Accept either liner with two supporting numbers.
Award two points for a clear recommendation supported by two figures taken from items 3 through 10, one point for a reasonable open question, and one point for writing that connects the numbers to the choice. A common strong answer picks Liner B, noting it saves 2,280 gallons a day against Liner A's 1,440 while costing only $150 more each year. A defensible answer also picks Liner A, noting its lower yearly cost and the fact that 1,440 gallons a day may already meet the farm's target. Open questions worth credit include how much the farm pays for water, whether the pond can be drained long enough to install a sheet liner, whether equipment can reach the site, and how each liner holds up against roots and animals.
Differentiation
Support
Give these students a version with items 3 and 4 set up as labeled multiplication frames, and a printed reminder that a percent of a quantity is found by multiplying. Reduce the test to items 1 through 9 and item 12, scaled to a smaller total. Allow them to answer item 12 orally to the teacher while pointing at the figures they used.
Extension
Ask students to work out how many seasons of saved water it would take for each liner to pay back its purchase price, if the farm values irrigation water at a rate the class agrees on together. Have them explain in writing why that answer depends on a number the test never supplied, and what that says about design decisions made with missing data.
ELL supports
Provide a labeled diagram of the pond showing length, width, and depth, with an arrow at the bottom marked seepage. Pre-teach liner, seepage, and yearly cost with picture cards. Give the sentence frame "I recommend Liner ___ because it saves ___ gallons a day and costs ___ each year" for item 12, and allow item 2 to be completed with the frame "The liner must ___ by at least ___."
Extensions
Have students rewrite item 12 as a short letter to the orchard owner, keeping the same two numbers but adding one sentence about what the farm should measure after the liner goes in. Ask them to name the measurement, how often it should be taken, and what result would show the liner is failing. This turns a one-time recommendation into a monitoring plan, which is what a real design team would hand over with the work.