Quiz & test questions Grade 4 Engineering & Design
Ellaby Island Camp's Dry Month: Comparing Three Water Plans
A grade 4 design-review quiz in which students judge three water-supply plans for a fictional island camp against a supply target, a no-rain rule, and a token limit.
Objectives
- Students will sort design rules into criteria for success and constraints on spending.
- Students will judge three water-supply plans against the same set of camp rules.
- Students will explain a trade-off that comes with the plan they recommend.
Vocabulary
Key words: criteria, constraint, trade-off, solar still, rain catchment
Teacher overview
This 30-minute quiz is worth 24 points and mixes four multiple-choice items with four short-answer items. No item asks for a calculation; every judgment comes from reading the plan table against three stated rules. The misconception to expect is the belief that the plan with the biggest supply number, or the plan with the smallest price, wins automatically. Fourth graders frequently circle the boat plan because its gallon number is largest and never check it against the spending limit, so items 4 and 8 are written to make that habit visible and correctable in class discussion.
Assessment
Ellaby Island Camp is a fictional summer camp on a small island. Rain barrels supply the camp with water. In a dry month the barrels run low. The camp director asked a student team to study three plans. The table shows what the team found.
| Plan | Fresh water on a dry day | Cost in supply tokens | Days to set up | Works in a month with no rain |
|---|---|---|---|---|
| Plan 1: haul barrels by boat | 80 gallons | 30 | 1 | yes |
| Plan 2: add roof gutters and a catch tank | 0 gallons | 18 | 3 | no |
| Plan 3: a row of 20 solar stills | 12 gallons | 24 | 4 | yes |
A solar still is a shallow tray of sea water under a slanted cover. The sun warms the tray. Water rises as vapor, leaves the salt behind, and drips off the cover into a clean cup. The 12-gallon number comes from the team's own sunny-day test at the camp.
The camp director wrote three rules:
- The plan must supply at least 10 gallons of fresh water on every dry day.
- The plan must still work during a month with no rain.
- The camp may spend no more than 25 supply tokens.
- (2 points) Which rule is a limit on what the camp may use, rather than a goal the plan must reach?
- A) The plan must supply at least 10 gallons on a dry day.
- B) The plan must work in a month with no rain.
- C) The camp may spend no more than 25 supply tokens.
- D) The plan must be tested by students.
- (3 points) Which plan gives no fresh water at all on a day with no rain?
- A) Plan 1
- B) Plan 2
- C) Plan 3
- D) None of them
- (3 points) Which plan follows all three of the director's rules?
- A) Plan 1
- B) Plan 2
- C) Plan 3
- D) Plan 1 and Plan 3
- (3 points) Plan 1 supplies the most fresh water on a dry day. Explain why the camp still cannot choose Plan 1.
- (3 points) Name one thing the camp gives up by choosing Plan 3 instead of Plan 1.
- (3 points) Plan 2 fails the no-rain rule. Write one change to Plan 2 that could help the camp through a dry month.
- (3 points) The team wants to find out whether a wider still makes more fresh water than a narrow one. Which plan gives a fair test?
- A) Build one wider still and set it in the shade.
- B) Build one wider still, keep the same sunny spot and the same sea water, and measure the drips for the same number of hours.
- C) Build one wider still and fill it with pond water instead of sea water.
- D) Build two stills that are the same width and compare them.
- (4 points) A camper says that the cheapest plan is always the best plan. Use the table to explain why that is not true at Ellaby Island Camp.
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: C) The camp may spend no more than 25 supply tokens.
A limit on money, materials, or time is a constraint. Choices A and B describe what the finished plan has to do, which makes them criteria for success. - Answer: B) Plan 2.
The table lists 0 gallons on a dry day for Plan 2, because roof gutters only collect water while rain is falling. - Answer: C) Plan 3.
Plan 3 supplies 12 gallons, which clears the 10-gallon rule. It works with no rain. It costs 24 supply tokens, which is not above the limit of 25. Plan 1 costs 30 tokens and Plan 2 fails the no-rain rule. - Answer: Plan 1 costs more than the camp is allowed to spend.
Plan 1 costs 30 supply tokens, and the director set a limit of 25. A plan that breaks even one rule is out, no matter how good its other numbers look. - Answer: Much less fresh water each dry day.
Accept any answer supported by the table, such as far fewer gallons on a dry day, or the longer setup time of 4 days instead of 1. - Answer: Store rain water from wet months in a larger tank.
Accept any sensible change that keeps water on hand when rain stops, such as adding a bigger catch tank filled during rainy weeks, or pairing Plan 2 with a few solar stills. Do not accept a change that leaves the camp with nothing on a dry day. - Answer: B) Build one wider still, keep the same sunny spot and the same sea water, and measure the drips for the same number of hours.
A fair test changes one thing at a time. Choice B changes only the width. Choices A and C change a second thing, and choice D never changes the width at all. - Answer: The cheapest plan does not meet the camp's rules.
Plan 2 costs the fewest supply tokens, yet it supplies 0 gallons on a dry day and fails the no-rain rule. The plan worth choosing is the cheapest one that still meets every rule, which is Plan 3.
Differentiation
Support
Give students a copy of the table with the three rules printed directly beneath it, and work item 3 as a class by crossing out one plan at a time, one rule at a time. Offer a word bank for items 4 through 6 containing tokens, limit, rain, gallons, and store. Accept a labeled arrow drawn on the table in place of a written sentence for item 5.
Extension
Ask students to write a fourth plan that would supply more than 12 gallons on a dry day while staying at or under 25 supply tokens, and to name the number in their plan they are least sure about. Then have them describe the one test they would run at camp to check that number before the director spends anything.
ELL supports
Pre-teach gutter, barrel, haul, still, and vapor with quick sketches, and demonstrate a solar still using a bowl of salty water, plastic wrap, and a small cup in the center; students observe the collected water but do not taste it. Provide sentence frames for the short-answer items: "Plan 1 cannot be chosen because ____." and "By choosing Plan 3, the camp gives up ____."
Extensions
Have students compare the camp's problem with the choices a coastal town faces during a long drought, where the same three families of answers appear at a much larger size: trucking or piping water in, catching and storing more of what falls, and taking the salt out of sea water. Ask which of the camp's three rules would still matter to a town, which new rules a town would have to add, such as keeping the water safe to drink and keeping the power bill payable, and where those new rules would change the winning plan.