HS-ETS1-1: Specifying Criteria and Constraints for a Global Challenge
In plain English: HS-ETS1-1 is the NGSS high school performance expectation that asks students to analyze a major global challenge, such as clean water, food or energy, and specify what any solution must achieve and what limits it must respect. Students write qualitative and quantitative criteria and constraints that reflect what people need and want. It is usually taught inside a high school science or engineering course.
Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
Next Generation Science Standards · Disciplinary Core Idea: Engineering Design · Official standard
Before anyone designs a solution to a global challenge such as safe drinking water, food that does not spoil or cleaner cooking fuel, someone has to say exactly what a good solution must do and what limits it has to respect. In this lesson students analyze a challenge with data and stakeholder statements, and they write the specifications: criteria (what success looks like) and constraints (limits that rule out some designs), each either qualitative (described in words) or quantitative (a number with a unit). They trace every specification back to a societal need or want, and they quantify wherever they can. The practice is Asking Questions and Defining Problems, and the core idea is ETS1.A, Defining and Delimiting Engineering Problems: criteria and constraints include requirements set by society, and they should be quantified to the extent possible and stated so that one can tell whether a given design meets them.
NGSS gives no Clarification Statement and no Assessment Boundary for HS-ETS1-1, so this lesson stays with the wording of the performance expectation: every task starts from a major global challenge, usually through the form it takes in one community, and ends with specifications, not with a finished design. All community data, prices and test results on this page are invented for teaching and labeled as invented. The filter lab uses tap water, soil and sand only, with goggles, and nobody drinks any sample.
Learning Objectives
By the end of this lesson, students will be able to:
Describe a major global challenge and the form it takes in a specific community, using data and stakeholder statements
Distinguish criteria from constraints, and qualitative specifications from quantitative ones
Derive quantitative criteria and constraints from data, with correct units and calculations
Rewrite vague wants as specifications someone could test, and explain when a specification should stay qualitative
Trace each specification to a societal need or want and justify which ones have priority
Prior Knowledge Required
Students should already be comfortable with:
Defining the criteria and constraints of a design problem MS-ETS1-1
Designing a method to monitor and reduce a human impact on the environment MS-ESS3-3
Unit conversions for volume, mass and time (liters, cubic meters, kilograms, tonnes, hours)
Tell students that many communities around the world have no safe water source near their homes. Give them three minutes alone and three minutes with a partner.
Warm-Up Prompt
"A village has no safe water source near homes, and families walk to a river. You are writing instructions for the engineers who will design a new water supply. List everything a good solution must do, then everything that limits what they can build."
Collect answers on sticky notes and sort them into two columns on the board: must do (clean water, enough water, close to homes, safe to reach) and limits (money, time, spare parts, what the community will accept). Name the two columns: criteria and constraints. Then ask which notes a stranger could check with a measurement. Most notes are words, not numbers. Tell students that the job today is to turn this kind of list into specifications an engineer could design against.
Direct Instruction20 minutes
Four kinds of specification. A criterion says what a successful solution achieves. A constraint is a limit that rules out some solutions, such as a budget, a deadline, a law or the parts available. Each can be qualitative, stated in words and judged by people, or quantitative, stated with a number and a unit so a measurement can decide it. Diagram 1 shows one of each type for a community water supply.
Describe the challenge where it happens. A global challenge (safe water, food, clean energy) always shows up in a particular place. Name the community, its size and the data you have.
List the stakeholders: the people who use, pay for, build, maintain or are affected by any solution. Record what each one needs and what each one wants.
Separate needs from wants. A need is required for health, safety or basic function. A want makes a solution better or more likely to be used, and it can still matter a lot.
Write the criteria and the constraints as short, testable statements, and label each one qualitative or quantitative.
Quantify wherever you can: turn a per-person figure into a total, a budget into a cost per person, a deadline into months. Keep units on every number.
Keep a qualitative specification qualitative when a number would miss the point (for example community approval), but say who judges it and how.
Rank the specifications: needs come before wants, and a trade-off later in the design will depend on this ranking.
Worked example: a water supply for a community of 1,200 people (invented data). The planning team uses 20 L of safe water per person per day (see the split in Diagram 2), has a grant of $54,000 for equipment, and must be finished within 9 months, before the dry season.
Design brief for the community water supply (invented data)
Specification
Type
Comes from
Supplies at least 24 m³ of safe water per day
Quantitative criterion
Need: health of 1,200 people
No E. coli found in any 100 mL sample
Quantitative criterion
Need: health (the WHO guideline value)
Water has no taste or odor residents object to
Qualitative criterion
Want that decides use: families may return to the river
Tap stands feel safe to use after dark
Qualitative criterion
Need: safety of people collecting water
Capital cost at most $45 per person
Quantitative constraint
Grant of $54,000
Installed within 9 months
Quantitative constraint
Dry season deadline
Local mechanics can repair it with parts sold in the district
Qualitative constraint
Need: the system must keep working
The community council approves the site
Qualitative constraint
Societal requirement: local decision-making
Quantitative criterion from a need
1,200 people each need 20 L of safe water per day. Convert the total to cubic meters (1 m³ = 1,000 L).
Result: 1,200 × 20 L = 24,000 L = 24 m³: the supply must deliver at least 24 m³ per day
Quantitative constraint from a budget
A $54,000 grant must pay for equipment that serves all 1,200 people.
Result: $54,000 ÷ 1,200 = $45: capital cost at most $45 per person
Qualitative criterion
Residents say that chlorinated water "tastes like a swimming pool". If the water tastes wrong, families may keep using the river.
Result: Treated water has no taste or odor residents object to, judged by a panel of residents
Qualitative constraint
The nearest pump dealer is a day away, and a broken pump elsewhere in the district stayed broken for months.
Result: Every part can be repaired by a local mechanic with parts sold in the district
Stress two points. First, the taste criterion is a want, yet it can decide whether the safe water is used at all, so it earns a high rank. Second, quantifying changes a statement from an opinion into a test: "enough water" can be argued about, but "at least 24 m³ per day" can be measured with a flow meter.
Guided Practice15-20 minutes
Groups of three analyze a second global challenge with you: smoke from cooking fires inside homes. Show the invented baseline data from one district and the program goals.
Cooking in one district: invented baseline data and goals
Item
Now
Goal or limit
Wood burned per household
3.5 kg per day
Cut by at least 40%
Fine-particle smoke (PM2.5) in the kitchen while cooking
500 µg/m³
Cut by at least 80%
Time to cook the evening meal
90 minutes
No longer than now
Price families say they can pay
At most $20 per stove
Pot used for the main dish
Round-bottomed clay pot
Stove must hold it steady
Ask each group to (1) turn the two percentage goals into quantitative criteria with units, (2) label every row as a criterion or a constraint, qualitative or quantitative, (3) add one qualitative constraint the table is missing, and (4) mark each row as a need or a want. Walk the room: the wood criterion is at most 3.5 × 0.6 = 2.1 kg per day, and the smoke criterion is at most 500 × 0.2 = 100 µg/m³ in the kitchen. The price is a quantitative constraint and the pot is a qualitative constraint. A good missing constraint is "built from materials a local workshop can supply". Point out that a stove that cannot hold the family's pot will not be used, however clean it burns.
Independent Practice10-15 minutes
Each student picks one challenge: flooding in a coastal town, electricity for a school far from the grid, plastic waste carried by a river, or stored grain that spoils before it is eaten. On one page they name the community, list three stakeholders, and write eight specifications, two of each kind in Diagram 1. Each specification is labeled need or want and names the stakeholder it comes from. Collect the pages; they are the starting point for Homework Problem 6.
Closure5-10 minutes
Exit Ticket
"Write one new criterion and one new constraint for the village water supply that are not in the design brief, one qualitative and one quantitative. For each, name the need or want it comes from."
Look for correct labels (a criterion describes success, a constraint limits the options), a unit on the quantitative one, and a clear link to a stakeholder. Examples: "a tap stand within 400 m of every home" (quantitative criterion, need) or "the design does not need fuel the families must buy" (qualitative constraint, need).
Differentiation Strategies
For Struggling Students
Give a four-box organizer shaped like Diagram 1 and have students place each sticky note in a box before writing their own
Provide sentence frames: "A good solution must ___ (criterion)" and "Any solution is limited by ___ (constraint)"
Work one per-person calculation together (people × liters per person) before students quantify on their own
For Advanced Students
Ask students to find two specifications in the water brief that pull against each other and describe the trade-off a designer will face
Have students look up one real public data source for their chosen challenge (a national statistics office or a UN agency) and revise a quantitative specification with it, citing the source
Ask students to write a test procedure for one qualitative criterion that keeps it qualitative but makes the judging fair
Assessment Guidance
What to Look For
Strong work names a real community and its people before it lists specifications. Criteria and constraints are not mixed up, every quantitative specification has a unit and comes from data or a stated calculation, and qualitative specifications say who judges them. Each specification traces to a need or a want, and the student ranks needs above wants. Watch for vague words (cheap, strong, enough) with no number, specifications that describe a solution ("use a solar pump") instead of what any solution must do, and lists that ignore the people who will use and maintain the design.
02
Classroom Activities
3 Activities
1
Stakeholder Role Cards: Grain That Spoils
20 minGroups of 6 (one card each)
In many farming regions, a large share of the grain harvest is lost to insects, mold and damp before families can eat or sell it. Each group analyzes this challenge in one invented farming village. Every student takes one of the 6 role cards, speaks for that stakeholder, and the group turns what they hear into specifications for a storage solution.
The 6 Role Cards
Farmer: "I need to keep my maize for 8 months, until prices rise. I can spend at most $30 a season on storage."
Family cook: "I want to keep insects out without handling chemicals near our food."
Grain trader: "I only buy maize that is dry and has no mold. I test every sack."
Extension officer: "Any method must be learned in a one-hour village meeting."
Village council member: "The storage must fit inside homes or the existing village store."
Health officer: "No pesticide residue in food, and used plastic must be collected, not burned."
Procedure
Each stakeholder reads the card aloud; the group writes every need and want on its own sticky note
Turn each note into a specification and place it on a four-box chart like Diagram 1
Quantify at least three specifications. Where a card gives no number (the trader's "dry"), write what data you would need to find one
Mark each specification N (need) or W (want), then rank the top five
Discussion Questions
Which two cards pull against each other? Which one should win, and why?
The trader says "dry" but gives no number. How would you turn that into a quantitative criterion, and who could tell you the right value?
Which specification did your group keep qualitative on purpose?
Modification for Distance Learning
Assign the six roles in a video call and post the cards in the chat. Each group builds its four-box chart on a shared slide, then one member presents the top five specifications.
2
Filter Flow Lab: Measuring to Set a Criterion
30 minGroups of 3
Groups build a simple sand-and-gravel filter, measure how fast it passes muddy water and how clear the water comes out, and use the data to write a realistic quantitative criterion for a household filter. The point is not to make drinking water: it is to see how measurements turn a vague want ("filters fast enough") into a number.
Safety
Everyone wears safety goggles while pouring muddy water
This filter does not make water safe to drink. Nobody drinks or tastes any sample, filtered or not
The teacher cuts the bottles before class and covers the cut edges with tape; students do not use blades
Use only tap water, garden soil, clean play sand and aquarium gravel. Pour waste water into the bucket (not the sink) and empty it outdoors
Wipe up spills at once so nobody slips, and wash hands with soap at the end
Procedure
Stand the cut bottle upside down in a jug. Layer, from the neck up: a cotton ball, 5 cm of sand, 5 cm of gravel
Mix 1 L of tap water with 2 spoonfuls of garden soil and stir
Pour it in all at once and start the stopwatch. After 4 minutes, read the volume collected
Set a clear cup of filtered water on the X card and rate the clarity: 0 = X not visible, 1 = X blurry, 2 = X clear but water tinted, 3 = X sharp
Record both numbers on the class table
Sample Class Data (invented)
Volume collected in 4 minutes and clarity rating: Group A 0.72 L, clarity 2; Group B 0.80 L, clarity 2; Group C 0.64 L, clarity 3; Group D 0.88 L, clarity 1. Mean volume 0.76 L, so the mean flow rate is 0.76 ÷ 4 = 0.19 L per minute.
A household of 5 at 20 L per person needs 100 L a day. At the mean rate one bottle filter would need about 526 minutes, almost 9 hours of pouring.
Discussion Questions
Families say they will spend at most 2 hours a day filtering. What flow rate does a household filter need, and how many times faster is that than the class mean?
Group D had the fastest flow and the lowest clarity, and Group C the slowest flow and the highest clarity. What trade-off does that show, and how should the criteria handle it?
The clarity scale is a qualitative judgment turned into a number. What would a real quantitative criterion for clarity need?
3
Critique a Design Brief: A Clinic Vaccine Refrigerator
20 minPairs
Keeping vaccines cold on the way to remote clinics is part of the global challenge of health care for everyone. Pairs review a weak design brief written for a refrigerator at one rural clinic and rewrite it using the invented clinic data.
The Brief and the Data
The brief: (1) The fridge must keep vaccines cold. (2) It should be cheap. (3) It must hold enough vaccine. (4) It must look modern. (5) It must run on solar power.
Invented clinic data: many vaccines must be stored between 2 °C and 8 °C; one month of vaccine stock takes 18 L of fridge space; deliveries are monthly but can arrive up to 2 weeks late; the grid fails often, and the longest outage last year lasted 3 days; the health ministry will pay up to $3,500; one nurse runs the clinic.
Procedure
Label each line of the brief: criterion or constraint, qualitative or quantitative, need or want
Rewrite lines 1, 2 and 3 as quantitative specifications using the data. For line 3, store enough for the longest wait between deliveries
Decide whether line 5 is a real constraint or a solution someone already chose, and rewrite it as what any solution must do
Add one qualitative constraint that comes from the nurse
Discussion Questions
Line 3 becomes "at least 27 L of storage at 2-8 °C". Where does the 27 come from?
Why is "keeps 2-8 °C for 3 days without power" a better specification than "must run on solar power"?
Line 4 is a want. Is there any reason to keep it?
03
Diagrams & Visual Aids
2 diagrams
Diagram 1: Four Kinds of Specification for a Community Water Supply
Criteria (top row) say what a successful water supply achieves; constraints (bottom row) are limits that rule out some designs. The left column is qualitative, judged in words by people; the right column is quantitative, decided by a measurement. The 24 m³ and $45 values come from the worked examples.
Diagram 2: Where 20 Liters per Person per Day Go
An invented planning split of the 20 L per person per day used in the worked example, drawn to scale (50 pixels per liter). Adding the four uses gives the per-person figure, and multiplying by the population gives the quantitative criterion for the whole supply.
04
Homework Assignment
~30 min
HS-ETS1-1 Homework: Writing Specifications for a Global Challenge
Directions: Show every calculation with units. Label every specification as a criterion or a constraint, and as qualitative or quantitative. All data are invented for practice.
Part 1: Analyzing the Challenge (Problems 1-3)
A coastal town faces more frequent flooding from storm surges. Stakeholders said: (a) "Homes in the low district must stay dry during a storm surge of 2.4 m above high tide." (b) "The total cost cannot exceed $30 million." (c) "Fishing boats must still be able to reach the harbor." (d) "The shoreline should still look natural from the beach." (e) "Construction must be finished within 4 years." (f) "The barrier must last at least 50 years with maintenance." (g) "The project must follow the national law that protects sea turtle nesting beaches." (h) "We would like a walking path along the top." Classify each statement in two ways (criterion or constraint; qualitative or quantitative), mark it need or want, and name two statements that may conflict.
Plastic waste carried by rivers is a global challenge. A town plans a floating barrier to catch plastic on its river. Invented data: the river is 60 m wide and carries about 1.5 tonnes of floating plastic per week; boats need a navigation gap at least 12 m wide; a collection crew can remove at most 250 kg per trip and make 5 trips a week. The town's goal is to capture at least 80% of the floating plastic. (a) Write the capture goal as a quantitative criterion in tonnes per week. (b) Write the navigation gap as a quantitative constraint on the barrier's length, and give it as a percent of the river width. (c) Does the crew limit allow the criterion to be met?
A team designs a water kiosk for a large refugee settlement. Residents say they want it to be "safe for children", "not wasteful", "private enough for washing" and "quiet at night". For each want, either rewrite it as a quantitative criterion someone could test, or explain why it should stay qualitative and say who would judge it and how.
Part 2: Specifying and Defending (Problems 4-6)
A coastal town's record storm surge reached 2.1 m above normal high tide. Planners add 0.5 m for expected sea-level rise over the barrier's 50-year life and 0.3 m of extra height as a safety margin. (a) What is the minimum crest height of the barrier? (b) The barrier is 1.8 km long and costs about $3,900 per meter at that height. The budget is $7.5 million. Does the design meet the cost constraint, and by how much? (c) A new report says the sea-level allowance should be 0.8 m, which raises the cost to $4,400 per meter. What happens to the cost constraint, and which specification would you ask the town to reconsider?
A team surveyed 80 households (invented data) about a household water filter. 62 said it must cost under $10, 48 said it should treat 20 L at a time, 71 said it must not change the taste of the water, and 22 said they would like it in a bright color. (a) Give each result as a percent. (b) Using the data, write four specifications, and label each as a need or a want. (c) Which specification would you rank first, and why?
Choose the challenge from your Independent Practice page (or another major global challenge approved by your teacher). Write a one-page design brief: describe the challenge and the community where it shows up, list at least three stakeholders, and write at least two specifications of each kind (qualitative criterion, quantitative criterion, qualitative constraint, quantitative constraint). Label each as a need or a want, show the data or calculation behind every number, and rank your top three specifications with a reason.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
No Credit (0 pts)
Challenge Analysis
Names the community, the stakeholders and the data behind the challenge
Challenge described but stakeholders or data missing
No analysis of the challenge
Classification
Every specification correctly labeled criterion or constraint, qualitative or quantitative
One or two labels wrong
Criteria and constraints confused throughout
Quantification
Numbers come from data or correct calculations, with units
Correct method with one error or missing units
No numbers, or numbers with no basis
Needs, Wants and Priority
Each specification traced to a need or want, with a justified ranking
Needs and wants labeled but no ranking or reason
No link to the people affected
05
Quiz: 20 Questions
Interactive, with answers
Instructions
Choose an answer for each multiple-choice question to see whether it is right and why. The last six questions are short answer: write your answer first, then open the sample answer. Reset quiz clears your choices. All data in the questions are invented for practice.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
A team is designing a household water filter. Which of these is a constraint rather than a criterion?
Answer: C
A price ceiling is a limit that rules out some designs, so it is a constraint (a quantitative one). Choices A, B and D describe what a successful filter achieves, so they are criteria. Choice D is the tempting one: it is qualitative, but being qualitative does not make it a constraint.
Question 2 of 20 · Multiple Choice
A coastal city is designing a system to keep plastic bottles out of the sea by collecting them for recycling. Which statement is a quantitative criterion?
Answer: B
Choice B says what success looks like and gives a number that bottle sales and recycling records can check. Choice A is a qualitative criterion (a want). Choices C and D are qualitative constraints: they limit which designs are allowed but do not say what the system must achieve.
Question 3 of 20 · Multiple Choice
A team is lighting a school that has no grid electricity. Which is a qualitative constraint?
Answer: D
Following a safety code limits which designs are allowed and is stated in words, so it is a qualitative constraint. Choice A is a quantitative constraint (a power limit), choice B is a quantitative criterion, and choice C is a qualitative criterion: it describes success, not a limit.
Question 4 of 20 · Multiple Choice
Which is a qualitative criterion for a cleaner cookstove?
Answer: A
Choice A describes success and is judged by the people who use the stove, not by an instrument, so it is qualitative. Choice B is a quantitative criterion. Choice C is a quantitative constraint, and choice D is a qualitative constraint about the supply chain.
Question 5 of 20 · Multiple Choice
A settlement of 850 people plans for 15 L of safe water per person per day. What quantitative criterion should the supply meet?
Answer: D
Total = 850 people × 15 L per person = 12,750 L per day (about 12.8 m³). Choice A divides 850 by 15, choice B drops a zero from the product, and choice C adds the two numbers instead of multiplying.
Question 6 of 20 · Multiple Choice
A grant of $36,000 must pay for water filters for 900 households. What is the cost constraint per household?
Answer: C
$36,000 ÷ 900 = $40 per household, so any filter above $40 is ruled out. Choice A divides 900 by 36, and choices B and D misplace the decimal point by a factor of 10.
Question 7 of 20 · Multiple Choice
Residents of a town that floods made these statements. Which one is a want rather than a need?
Answer: C
Murals make the design more pleasant and may win public support, but nobody's health or safety depends on it, so it is a want. Choices A, B and D protect health and safety, so they are needs that rank above it.
Question 8 of 20 · Multiple Choice
Why do engineers quantify criteria and constraints whenever they can?
Answer: B
A number with a unit turns an opinion into a test, so two people judging the same design reach the same answer. Choice C is false: some specifications, such as community approval, should stay qualitative. Choices A and D are not reasons to quantify.
Question 9 of 20 · Multiple Choice
A farm stores 3.0 tonnes of maize. Traditional storage loses 20% of it; the new storage must lose at most 6%. What is the largest loss the new storage may allow?
Answer: A
6% of 3.0 t = 0.18 t = 180 kg, so the criterion is "loses at most 180 kg of the 3.0 t". Choice B is the current loss (20% of 3,000 kg), choice C is the grain saved (600 - 180), and choice D takes 6% of 300 kg, as if 1 tonne were 100 kg instead of 1,000 kg.
Question 10 of 20 · Multiple Choice
Which rewrite turns "the pump should be easy to use" into a criterion someone could test?
Answer: D
Choice D names who, what and how fast, so a trial can decide it. Choices A and C still use the vague words "easy to use", and choice B changes the subject from use to appearance.
Question 11 of 20 · Multiple Choice
An aid flight can carry 12,000 kg. Of that, 1,500 kg must be kept for water purification equipment. Each family water kit weighs 15 kg. What is the constraint on the number of kits?
Answer: B
Mass left for kits = 12,000 - 1,500 = 10,500 kg, and 10,500 ÷ 15 = 700 kits. Choice A ignores the equipment (12,000 ÷ 15), choice C divides the equipment mass by 15, and choice D drops a zero.
Question 12 of 20 · Multiple Choice
Which is a local form of the global challenge of energy sources that cause less pollution?
Answer: A
Smoky air from diesel buses is a local case of the need for energy that pollutes less, so a design team could analyze it under HS-ETS1-1. Choices B, C and D are real wants, but none is part of a major global challenge such as clean energy, water or food.
Question 13 of 20 · Multiple Choice
A team's criterion is "turbidity at most 5 NTU". Invented tests of four water sources gave W1: 3.2 NTU, W2: 6.8 NTU, W3: 4.9 NTU, W4: 12.5 NTU. Which sources meet the criterion?
Answer: B
Only 3.2 and 4.9 are at or below 5, so W1 and W3 pass. Choice A misses that 4.9 is below 5, choice C picks the sources that fail, and choice D treats 6.8 as passing. A quantitative criterion makes this decision a simple comparison.
Question 14 of 20 · Multiple Choice
A design brief says the household filter "must be cheap". What is the best improvement?
Answer: A
Choice A quantifies the constraint and ties it to the people who will pay. Choice B is still vague, choice C is wrong because cost is one of the main constraints on any design, and choice D moves the words without making them testable.
Question 15 of 20 · Short Answer
Many rural health clinics have no reliable electricity. For one such clinic, write one qualitative criterion, one quantitative criterion, one qualitative constraint and one quantitative constraint for a power system, and label each as a need or a want.
Sample answer. Qualitative criterion: the nurse can see the system's charge level at a glance (want). Quantitative criterion: the delivery room has at least 6 hours of light each night (need). Qualitative constraint: the equipment can be serviced by a technician in the district (need). Quantitative constraint: the installed cost is at most $4,000 (need, set by the budget). Any set with correct labels, a unit on each number and a clear link to a need or want earns full credit.
Question 16 of 20 · Short Answer
During a drought, a city of 400,000 people wants to cut household water use from 180 L to 150 L per person per day. Write the goal as a quantitative criterion for the whole city in cubic meters per day, and add one qualitative constraint that accounts for a societal need.
Saving per person = 180 - 150 = 30 L per day. City-wide saving = 400,000 × 30 L = 12,000,000 L = 12,000 m³ per day (1 m³ = 1,000 L). Criterion: household use falls by at least 12,000 m³ per day (to at most 60,000 m³ per day). A qualitative constraint: the measures must not leave any household, including low-income ones, without enough water for drinking and hygiene.
Question 17 of 20 · Short Answer
A team is designing cold storage for fish sellers at a market with no reliable electricity. Classify each statement as criterion or constraint, qualitative or quantitative, and need or want: (a) "Fish stays at or below 4 °C for 10 hours." (b) "Each stall's cooler costs at most $150." (c) "The stalls keep their traditional open look." (d) "The cooler works without mains electricity."
(a) Quantitative criterion, need (food safety). (b) Quantitative constraint, need (what sellers can pay). (c) Qualitative criterion, want (it matters to sellers and customers, but no one's safety depends on it; some students may call it a constraint, which is acceptable if they explain that it rules out closed buildings). (d) Qualitative constraint, need (the power supply is unreliable).
Question 18 of 20 · Short Answer
A student writes: "Criteria: the house is strong. Constraints: the house survives an earthquake." Name two problems with these specifications and rewrite them.
Problem 1: "strong" is vague; nobody can test it. Problem 2: surviving an earthquake says what success looks like, so it is a criterion, not a constraint, and it needs a measurable level, such as the shaking the local building code requires. A rewrite: criterion "the house stays standing and repairable after the level of shaking set in the local building code"; constraints "the house costs at most $12,000 and uses materials sold in the region". Any rewrite that makes the criterion testable and gives real limits as constraints earns full credit.
Question 19 of 20 · Short Answer
Explain, with an example from a global challenge, why a qualitative constraint about what a community accepts can decide whether a technically good solution succeeds.
Sample answer: a sanitation program builds well-designed latrines without asking families about privacy. If the doors face the main path where neighbors walk, many families may refuse to use them, and the health problem stays. The constraint "placed and built so users have the privacy the community expects" is qualitative, but ignoring it makes the solution fail. Specifications have to account for what people need and want, not only for what can be measured.
Question 20 of 20 · Short Answer
Invented data for a village: 640 residents, a planning figure of 18 L of safe water per person per day, and a grant of $32,000 for equipment. Write two quantitative specifications from these data and label each as a criterion or a constraint.
Criterion: the supply delivers at least 640 × 18 = 11,520 L per day (about 11.5 m³) of safe water. Constraint: equipment costs at most $32,000 ÷ 640 = $50 per person (or $32,000 in total).
0 of 20 answered · 0 correct
06
Frequently Asked Questions
10 Questions
What does HS-ETS1-1 mean?
HS-ETS1-1 asks high school students to analyze a major global challenge and specify the criteria and constraints that any solution must meet, in words and in numbers.
The specifications must account for what people need and want. The code reads: HS (high school), ETS1 (Engineering Design), performance expectation 1.
What is the difference between criteria and constraints?
Criteria say what a successful solution achieves; constraints are limits that rule out some solutions.
"Delivers 24 m³ of safe water per day" is a criterion. "Costs at most $45 per person" and "uses parts sold in the district" are constraints. When students are unsure, ask: does this describe success, or does it limit the options?
What is a qualitative criterion, and how is it different from a quantitative one?
A qualitative criterion is stated in words and judged by people; a quantitative one has a number and a unit that a measurement can decide.
"Tap stands feel safe to use after dark" is qualitative. "Supplies at least 24 m³ of safe water per day" is quantitative. HS-ETS1-1 asks for both, and quantifying where possible makes it clear whether a design meets the specification.
What counts as a "major global challenge" in HS-ETS1-1?
A problem that affects large numbers of people in many places, such as supplies of clean water and food, or energy sources that cause less pollution.
The NGSS core idea behind this standard notes that these challenges also show up in local communities. Classes usually work with one local form of the challenge, which gives them real data and real stakeholders.
What are "societal needs and wants" in HS-ETS1-1?
Needs are what people require for health, safety and basic function; wants are what makes a solution better or more likely to be used.
Both shape the specifications. A want, such as water that tastes normal, can decide whether a safe solution is used at all. Requirements set by society, such as laws and local approval, also belong in the constraints.
Do students have to design a solution for HS-ETS1-1?
No. HS-ETS1-1 stops at specifying what a solution must do and what limits it faces.
Designing the solution by breaking the problem into parts is HS-ETS1-2, evaluating it against trade-offs is HS-ETS1-3, and testing it with a computer simulation is HS-ETS1-4. Many classes teach HS-ETS1-1 as the first step of a longer project.
What mistakes do students make when they write criteria and constraints?
Vague words with no number (cheap, strong, enough), and specifications that describe a chosen solution instead of what any solution must do.
"Must run on solar power" is an example: the real specification may be "keeps working during a 3-day power cut". Students also mix up criteria and constraints, and they forget the people who will maintain the design.
Which science course teaches HS-ETS1-1?
Any of them: engineering design is meant to be taught inside the high school science courses.
Biology classes often use food or health challenges, chemistry classes water treatment, Earth science classes flooding or resources, and physics classes energy. Some schools also teach it in an engineering course.
Where can students find real data for a global challenge?
From public sources such as national statistics offices, city and water utility reports, and United Nations agencies such as the World Health Organization.
Ask students to cite each source next to the number it supports. When real data are not available, invented data are fine for practice, as long as they are realistic and labeled as invented.
How is HS-ETS1-1 assessed?
Through tasks where students analyze a challenge and write specifications, not through vocabulary recall.
State science tests aligned to NGSS handle engineering performance expectations in different ways, so check your state's test documents. In class, the homework rubric scores the analysis of the challenge, the classification, the quantification and the link to needs and wants.
07
Related Standards
5 standards
These standards connect to HS-ETS1-1: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
MS-ETS1-1Prerequisite
Define a design problem's criteria and constraints precisely enough to succeed
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