- Ice cream transport design challenge: Hold 1 liter of ice cream and keep it at or below -5°C for 30 minutes. Constraints: cost under $15, portable, doesn't leak, food-grade safe materials.
Which option correctly labels each statement as either a criterion or a constraint?
Answer: "Keep ≤ -5°C for 30 minutes" is a criterion; "under $15" is a constraint.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: maintain ≤-5°C temperature, work for 30 minutes duration, hold 1 liter capacity, prevent leaking), which are measurable targets that testing will verify; and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: cost under $15 budget, must be portable, materials must be food-grade safe). The distinction between criteria and constraints is fundamental: criteria describe WHAT the design must achieve (performance goals like temperature maintenance), while constraints describe limits on HOW you can achieve it (restrictions like budget or material choices). For ice cream transport: Criteria (performance goals) include "keep ≤-5°C for 30 minutes" (the ice cream must remain frozen—this is what success looks like), "hold 1 liter" (capacity requirement—another performance goal), and "no leaking" (functional requirement—melted ice cream must not escape). Constraints (limitations) include "under $15" (budget limit—restricts material and design choices), "portable" (usability limit—must be carriable by one person), and "food-grade materials" (safety limit—restricts material selection for food contact). Choice C is correct because it properly distinguishes criteria from constraints: "Keep ≤-5°C for 30 minutes" is correctly identified as a criterion (it's a performance goal—what the container must achieve), and "under $15" is correctly identified as a constraint (it's a limitation—a boundary within which the design must work). Choice A reverses these classifications incorrectly; Choice B incorrectly labels "hold 1 liter" as constraint when it's a performance criterion, and "food-grade materials" as criterion when it's a safety constraint; Choice D incorrectly labels "portable" as criterion when it's a usability constraint, and temperature maintenance as constraint when it's the primary performance criterion. Understanding this distinction guides design process: first identify what you need to achieve (criteria: keep ice cream frozen at ≤-5°C), then identify what limits your options (constraints: only $15 budget, must use food-safe materials), and finally design within constraints to meet criteria (find affordable food-safe insulation that maintains ≤-5°C for 30 minutes). The classification matters because criteria drive testing (did it stay ≤-5°C? measure and verify), while constraints drive design choices (what materials can I afford within $15? what's food-safe and insulating?).
- Cold drink cooler design challenge: Keep 12 cans at or below 10°C for 4 hours in 30°C weather. Constraints: budget $50, portable (handles or wheels), durable, materials limited to foam/plastic/ice packs.
A team proposes adding this requirement: "The cooler must weigh less than 2 kg."
How should this new requirement be classified?
Answer: It is a constraint because it limits the design's weight for portability.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: maintain ≤10°C temperature, work for 4 hours duration, hold 12 cans capacity), which are measurable targets that testing will verify; and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: $50 budget, must be portable with handles/wheels, must be durable for repeated use, materials limited to foam/plastic/ice packs). When adding new requirements, you must determine whether they describe what the design must achieve (criterion) or what limits the design must work within (constraint). The proposed requirement "must weigh less than 2 kg" sets a weight limit that affects design choices: it restricts material selection (heavy materials eliminated), limits insulation thickness (more insulation = more weight), affects ice/cooling capacity (ice adds weight), and ensures portability (lighter = easier to carry)—this is clearly a limitation on HOW the design can be built, not WHAT it must accomplish. Choice A is correct because weight limit is a constraint that limits the design's weight for portability—it's a boundary condition (maximum 2 kg) that restricts design options to ensure the cooler remains portable and practical to carry. Choice B incorrectly calls it a criterion about temperature, but 2 kg is weight not temperature; Choice C incorrectly calls it a criterion about duration, but weight doesn't describe how long the cooler works; Choice D incorrectly claims weight can't be measured, when scales easily measure weight in kg. Weight constraints are common in portable designs: they ensure usability (too heavy = hard to carry), affect material choices (aluminum vs steel, foam thickness), may conflict with performance (more insulation = better cooling but heavier), and require optimization (achieve cooling goals within weight limit). The distinction matters for design decisions: criteria tell you what to achieve (keep drinks ≤10°C for 4 hours), constraints tell you limits to work within (weigh ≤2 kg, cost ≤$50), and successful design meets all criteria while respecting all constraints (achieve temperature control using lightweight, affordable materials). Adding this weight constraint would require designers to carefully balance insulation effectiveness against weight, possibly using lightweight foam insulation, minimizing structural materials, and optimizing ice quantity to stay under 2 kg while still meeting the ≤10°C for 4 hours criterion.
- Design challenge (Cold drink cooler): At an outdoor event lasting 4 hours in 30∘C weather, you must keep 12 standard drink cans cold. The drinks must stay at or below 10∘C. The cooler must cost ≤$50, be portable (handles or wheels), and be durable for repeated use. Available materials include foam, plastic, and ice/ice packs.
Which statement best distinguishes criteria from constraints for this design?
Answer: Criteria describe what the cooler must do (temperature, time, number of cans), while constraints describe limits on how you do it (budget, portability, materials).
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: keep drinks ≤10°C, work for 4 hours duration, hold 12 cans), which are measurable targets that testing will verify (thermometer measures if temp ≤10°C met, timer measures if 4 hour duration met, count cans to verify capacity); and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: cost ≤$50 budget, must be portable with handles/wheels, durable for repeated use, materials limited to foam/plastic/ice), which bound the solution space preventing unlimited resources or unrealistic designs. The distinction is clear: criteria describe what the device must DO (maintain cold temp, hold volume, work for time), while constraints describe what you must work WITHIN (cost limit, portability requirement, material options)—criteria are achievements, constraints are boundaries. Choice B is correct because it properly distinguishes criteria from constraints (criteria describe what the cooler must do: temperature maintenance, time duration, capacity for number of cans; constraints describe limits on how you do it: budget restriction, portability requirement, material limitations). Choice A reverses the definitions (incorrectly calls limits "criteria" and goals "constraints"), Choice C incorrectly states they mean the same thing (they are fundamentally different: goals vs limitations), and Choice D confuses optional features with criteria (wheels are part of portability constraint, not criteria; temperature maintenance is criterion, not constraint). Establishing clear design requirements is the essential first step in engineering design process: understand the problem (keep drinks cold at outdoor event), set criteria defining success (specific measurable goals: maintain ≤10°C, work for 4 hours, hold 12 cans—know exactly what "success" means), establish constraints defining boundaries (realistic limits: budget $50, must be portable, use available materials—work within practical boundaries), make criteria testable (quantitative values allow objective pass/fail: thermometer reads 8°C at 4 hours = pass, reads 12°C = fail—no ambiguity), and ensure design satisfies both (achieve all criteria while respecting all constraints for successful solution).
- Cold drink cooler design challenge: Keep drinks at or below 10°C for 4 hours in 30°C weather and hold 12 cans. Constraints include budget $50, portability, durability, and materials (foam/plastic/ice packs).
Which requirement is most critical to prioritize as a temperature-control performance goal (criterion) for this application?
Answer: The cooler must keep the drinks at or below 10°C for 4 hours.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: maintain ≤10°C temperature, work for 4 hours duration, hold 12 cans capacity), which are measurable targets that testing will verify; and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: $50 budget, portability requirement, durability for reuse, materials limited to foam/plastic/ice packs). For a cold drink cooler, the most critical performance goal is temperature control: drinks must stay at or below 10°C for the full 4 hours in 30°C ambient temperature—this 20°C temperature difference represents significant heat gain that the cooler must resist, and warm drinks would fail the primary purpose of the cooler regardless of other features. Temperature control is the fundamental criterion because: (1) it's the core function—a cooler that doesn't keep drinks cold has failed its primary purpose, (2) it's challenging in 30°C weather—significant insulation and cooling capacity needed, (3) it directly affects user satisfaction—warm drinks at an outdoor event are unacceptable, and (4) other criteria depend on it—holding 12 cans means nothing if they're warm. Choice B is correct because it identifies the most critical temperature-control performance goal (criterion) for this application: "keep the drinks at or below 10°C for 4 hours" specifies both temperature target (≤10°C) and duration (4 hours), making it measurable and testable. Choice A about color preference is irrelevant to thermal performance and not a functional requirement; Choice C prioritizes low cost over function ("even if it doesn't work well"), which defeats the purpose—a cheap cooler that doesn't cool is useless; Choice D unnecessarily restricts materials to only plastic, eliminating foam and ice packs that are explicitly allowed and likely necessary for insulation and cooling. Prioritizing criteria is essential in design: identify the primary function (keep drinks cold), establish measurable performance goals for that function (≤10°C for 4 hours), ensure other criteria support the primary function (12 can capacity is secondary to temperature control), and work within constraints to achieve criteria (use $50 budget wisely to maximize cooling performance). The temperature criterion drives all design decisions: insulation thickness, ice/cooling capacity, seal quality, and material selection all serve to meet the ≤10°C for 4 hours requirement.
- Design challenge (Hot lunch container): Keep 500mL of soup at ≥60∘C from 7:00 AM until noon (5 hours). Constraints: cost under $20, height ≤15cm, safe exterior (no burn risk), and materials limited to plastic/foam/metal.
A student writes this requirement: "The soup should be warm at lunchtime."
Which revision makes this requirement a measurable criterion?
Answer: The soup must stay ≥60∘C for at least 5 hours, measured with a thermometer.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements must be specific and measurable to enable objective testing—vague requirements like "warm" or "long time" cannot be tested because there's no clear threshold for success (one person might consider 40°C "warm" while another expects 70°C, making evaluation subjective and inconsistent). For making criteria testable: Changing vague "keep soup warm at lunchtime" to specific "maintain ≥60°C for 5 hours" makes it testable: (1) measure starting temperature when soup added (ensure starts hot, >70°C ideally), (2) seal container, (3) wait 5 hours (or test at intervals: 1 hr, 3 hr, 5 hr), (4) measure final temperature with thermometer (read °C value), (5) compare to criterion (if ≥60°C then criterion MET ✓, if <60°C then NOT MET ✗), and (6) document results (60°C exactly is pass, 59°C is fail—clear threshold). Choice B is correct because it makes the requirement a measurable criterion (the soup must stay ≥60°C for at least 5 hours, measured with a thermometer—specific temperature threshold, specific time duration, specific measurement method, objective pass/fail determination). Choice A describes preferences not performance requirements (appearance and ease of opening don't relate to thermal performance), Choice C specifies a material which is a design decision not a criterion (foam might be good choice but criterion should state what to achieve, not how), and Choice D remains vague and untestable ("warm" has no specific temperature, "long time" has no specific duration—cannot objectively evaluate). Establishing clear measurable criteria enables: objective evaluation (everyone knows exactly what to achieve: ≥60°C, not subjective "warm enough"), clear testing procedures (use thermometer at 5 hours, compare to 60°C threshold), design comparison (Design A achieves 65°C, Design B achieves 58°C—A succeeds, B fails), and targeted improvement (if achieved 55°C, know need 5°C improvement in thermal performance). - Design challenge (ice cream transport): You need a container to transport 1 liter of ice cream from the store to home in 30 minutes. Criteria: keep the ice cream at ≤−5∘C during the trip and hold 1 liter. Constraints: cost under $15, portable (hand-carry), must not leak, and all materials must be food-grade.
Which statement correctly explains the difference between criteria and constraints in this challenge?
Answer: Criteria are what the design must accomplish (like ≤−5∘C for 30 minutes and holding 1 liter), while constraints are the limits you must work within (like under $15 and food-grade materials).
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: keep ice cream at ≤-5°C temperature for 30 minutes duration, hold 1 liter capacity), which are measurable targets that testing will verify (thermometer measures if temp ≤-5°C met, timer measures if 30 minute duration met, measuring cup verifies 1 liter capacity); and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: cost under $15 budget, portable for hand-carry, must not leak, all materials must be food-grade), which bound the solution space preventing unlimited resources or unsafe designs. The distinction between criteria and constraints is fundamental: criteria are what the design must accomplish (performance goals), while constraints are what you must work within (limitations on how to achieve those goals). Choice B is correct because it properly distinguishes criteria from constraints: criteria are what the design must accomplish (like ≤-5°C for 30 minutes and holding 1 liter—these are performance goals), while constraints are the limits you must work within (like under $15 and food-grade materials—these are boundaries). Choice A reverses the definitions incorrectly (cost is a constraint not criterion, temperature is criterion not constraint), Choice C incorrectly defines criteria as materials and constraints as testing methods, and Choice D wrongly claims they're the same when they serve distinctly different purposes. The ice cream transport example clearly shows: criteria define success (ice cream arrives frozen at ≤-5°C after 30 minutes, container holds full 1 liter portion), constraints define boundaries (can't spend more than $15, must be carriable by hand, can't use non-food-safe materials that would contaminate ice cream). Both are essential but serve different roles: criteria without constraints could be met with expensive solutions (industrial freezer unit), constraints without criteria leave unclear what to accomplish (cheap container but melted ice cream?). Clear distinction enables effective design: know what to achieve (criteria) and what limits to respect (constraints), guiding material selection, insulation choices, and testing procedures. - Design challenge: Laboratory sample storage for transport. Goal: keep biological samples at 4∘C for 8 hours. Criteria: temperature must stay from 2∘C to 6∘C for 8 hours; hold 200 mL; temperature monitoring required; shock-resistant. Constraint: total cost $\le $100.
Which proposed requirement is not appropriate because it is not measurable?
Answer: The device should be the safest possible.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria (2-6°C for 8 hours, hold 200 mL, monitoring, shock-resistant); (2) constraints (≤$100 cost). Both are essential, but criteria must be measurable for testability—vague terms like 'safest possible' are not. For making criteria testable: Specific temp range is measurable with thermometer, unlike subjective 'safest'. Specific measurable criteria enable objective evaluation and clear pass/fail. Choice B is correct because it identifies the non-measurable requirement ('safest possible' is subjective, not testable). Choice A is measurable (temp range); Choice C is measurable (volume); Choice D is measurable but a constraint. Establishing clear design requirements requires measurability for objective verification. Examples: GOOD: specific metrics; POOR: vague subjective terms.
- A lab needs to transport biological samples to a laboratory. The device must keep samples at 4∘C±2∘C (so the temperature must stay between 2∘C and 6∘C) for 8 hours. It must hold 200 mL of samples. Constraints: $100 budget, insulated, shock-resistant, and it must include temperature monitoring.
Which test best checks whether the design meets the temperature criterion?
Answer: Record the internal temperature with a thermometer/data logger over 8 hours and confirm it stays between 2∘C and 6∘C.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—like maintain 2-6°C for 8 hours, hold 200 mL, testable with measurements; (2) constraints—like $100 budget, insulated, shock-resistant. For sample transport, the temperature criterion is key and tested by monitoring over time to confirm it stays within range, distinguishing from tests for constraints like cost or weight. Choice B is correct because it appropriately makes requirements testable with specific measurable values (record temperature over 8 hours, confirm range). Choice A tests weight (possible portability constraint, not temperature); choice C tests cost (constraint); choice D is vague (shake once, subjective 'uncomfortable'). Establishing clear design requirements is the essential first step in engineering design process: set testable criteria to verify performance objectively and improve designs. - Cold drink cooler design challenge: You are designing a cooler for an outdoor event lasting 4 hours in 30°C weather. It must keep the drinks at or below 10°C. It must hold 12 standard cans. The budget is $50. It must be portable (handles or wheels), durable for repeated use, and you can use foam, plastic, and ice/ice packs.
Which option best identifies the constraints (limits) for this design?
Answer: Budget $50, must be portable and durable, and materials are limited to foam/plastic/ice packs
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: maintain ≤10°C temperature, work for 4 hours duration, hold 12 cans capacity), which are measurable targets that testing will verify (thermometer measures if temp ≤10°C met, timer measures if 4 hour duration met, count cans to verify 12 fit); and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: cost under $50 budget, must be portable with handles/wheels, must be durable for repeated use, materials limited to foam/plastic/ice packs), which bound the solution space preventing unlimited resources or unrealistic designs. For this cold drink cooler: The criteria (performance goals) are: (1) maintain ≤10°C (temperature criterion: drinks must stay cold and refreshing in hot weather, 10°C is cool enough for enjoyment, testable with thermometer at end of 4 hours), (2) duration of 4 hours (time criterion: length of outdoor event, must keep cold this long, testable with timer), and (3) capacity 12 cans (volume criterion: must hold enough drinks for event, testable by counting cans that fit). The constraints (limitations) are: (1) cost under $50 (budget constraint: event organizer can afford, eliminates expensive commercial coolers perhaps, testable by adding component costs), (2) portable with handles or wheels (mobility constraint: must move from storage to event location, testable by lifting/rolling), (3) durable for repeated use (longevity constraint: not single-use, must last multiple events, testable through repeated use cycles), and (4) materials limited to foam, plastic, ice packs (resource constraint: can't use exotic materials, limits design choices). Choice C is correct because it accurately identifies constraints as limitations (budget $50, portability requirement, durability need, and material restrictions—boundaries to work within). Choice A lists criteria (temperature and capacity goals), not constraints; Choice B describes a testing method, not a constraint or criterion; Choice D mixes a criterion (hold 12 cans) with vague language ("cold and refreshing") and doesn't identify constraints. Establishing clear design requirements is the essential first step in engineering design process: constraints define the boundaries within which you must work (can't exceed $50, must be portable, must use available materials), while criteria define what success looks like within those boundaries (keep drinks ≤10°C for 4 hours while holding 12 cans). The distinction is clear: criteria describe what the device must DO (maintain temp, hold volume, work for time), while constraints describe what you must work WITHIN (cost limit, portability requirement, material limit)—criteria are achievements, constraints are boundaries.
- Design challenge (Hot lunch container): A student packs 500mL of soup at 7:00 AM and wants it to still be safe to eat at noon (5 hours later). The soup must stay at or above 60∘C. The container must cost under $20, be no taller than 15cm so it fits in a backpack, and be safe to carry (the outside should not be hot enough to burn skin). Plastic, foam, and metal are available materials.
Which option lists only the criteria (performance goals the design must achieve)?
Answer: Keep soup ≥60∘C for 5 hours; hold 500mL; outside is safe to touch (no burn risk)
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: maintain ≥60°C temperature, work for 5 hours duration, hold 500 mL capacity, ensure safety with no burn risk from exterior), which are measurable targets that testing will verify (thermometer measures if temp ≥60°C met, timer measures if 5 hour duration met, pass/fail clear from measurements); and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: cost under $20 budget, size fits in backpack max 15 cm tall, materials limited to available foam/plastic/metal, safety requires food-safe materials), which bound the solution space preventing unlimited resources or unrealistic designs. For this hot lunch container: The criteria (performance goals) are: (1) maintain ≥60°C (temperature criterion: soup must stay at safe eating temperature, 60°C is minimum for hot food safety, testable with thermometer at end of 5 hours), (2) duration of 5 hours (time criterion: from 7 AM packing to noon eating, must keep hot this long, testable with timer), (3) capacity 500 mL (volume criterion: must hold a meal-sized portion, testable with measuring cup), and (4) safety (no burn hazard: exterior cool enough to touch even with hot soup inside, testable by touching exterior). The constraints (limitations) are: (1) cost under $20 (budget constraint: student/family can afford, eliminates expensive vacuum thermoses perhaps, testable by adding component costs), (2) size fits backpack (dimensions constraint: max 15 cm tall to fit with books, testable with ruler), and (3) materials available to foam, plastic, metal (resource constraint: can't use exotic materials not accessible, limits design choices). Choice B is correct because it correctly identifies criteria as measurable performance goals (temperature ≥60°C for 5 hours, hold 500 mL capacity, outside safe to touch—all things the design must achieve). Choice A lists only constraints (materials available, cost limit, size limit—all limitations to work within), Choice C mixes criteria and constraints (cost is constraint, keeping hot is criterion but vague), and Choice D mixes constraints (height limit) with criteria (safety) and adds unnecessary material restriction. Establishing clear design requirements is the essential first step in engineering design process: understand the problem (keep soup hot for school lunch), set criteria defining success (specific measurable goals: maintain ≥60°C, work for 5 hours, hold 500 mL—know exactly what "success" means), establish constraints defining boundaries (realistic limits: budget $20, size 15 cm, available materials foam/plastic—work within practical boundaries), make criteria testable (quantitative values allow objective pass/fail: thermometer reads 62°C at 5 hours = pass, reads 58°C = fail—no ambiguity), and prioritize if needed (for student lunch, temperature maintenance is critical for food safety, so that's the primary criterion). - Design challenge (hot lunch container): Keep 500 mL of soup at ≥60∘C for 5 hours (7:00 AM to noon). Constraints: under $20, max height 15 cm, safe exterior (no burn risk), materials limited to plastic/foam/metal.
Which requirement is most critical for food safety in this situation?
Answer: The soup must stay at ≥60∘C after 5 hours.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). For food safety applications, temperature control is often the most critical requirement because foodborne bacteria multiply rapidly in the "danger zone" between 4°C and 60°C—keeping hot foods above 60°C prevents bacterial growth that could cause illness, making this a health and safety issue not just a preference. The hot lunch container challenge involves keeping soup safe to eat after 5 hours, where maintaining proper temperature is essential to prevent foodborne illness that could result from bacterial growth in lukewarm soup. Among all requirements, the temperature criterion directly relates to whether the soup remains safe for consumption. Choice B is correct because it identifies the most critical requirement for food safety: the soup must stay at ≥60°C after 5 hours—this temperature threshold is based on food safety standards (above 60°C inhibits bacterial growth), directly impacts whether lunch is safe to eat (below 60°C enters danger zone), and represents the primary function of the thermal container (maintaining safe temperature). Choices A and C are constraints not criteria (height limit and cost limit are boundaries to work within, not safety goals), while Choice D about looking stylish is neither required nor related to food safety. The 60°C requirement is critical because: temperatures below 60°C allow rapid bacterial multiplication (doubling every 20-30 minutes), 5 hours provides ample time for dangerous bacterial levels if temperature drops, and consuming contaminated soup could cause food poisoning with serious health consequences. This demonstrates hierarchy in requirements: safety-critical requirements take precedence (must keep food safe), functional requirements support primary purpose (hold 500 mL, last 5 hours), and constraints guide practical implementation (cost, size, materials). When requirements conflict, safety wins: if meeting the $20 budget constraint would compromise the 60°C safety criterion, the design must either find creative solutions within budget or acknowledge the constraint cannot be met while maintaining safety. - Design challenge: Hot lunch container. Goal: keep 500 mL soup hot from 7:00 AM to noon (5 hours). Criteria: soup must be ≥60∘C at noon; capacity 500 mL; safe for students (no burn risk from exterior). Constraints: under $20; max height 15 cm; materials limited to plastic, foam, metal.
A student writes this requirement: "The soup should be hot at lunchtime." What is the best revision to make it a testable criterion?
Answer: The soup must be at least 60∘C at 12:00 PM (after 5 hours).
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria (≥60°C at noon, 500 mL, safe exterior); (2) constraints (under $20, max 15 cm, materials plastic/foam/metal). Both are essential for realistic goals. For making criteria testable: Changing vague 'keep soup hot' to specific 'maintain ≥60°C for 5 hours' makes it testable: measure with thermometer after 5 hours, compare to threshold. Specific measurable criteria enable objective evaluation: clear threshold (≥60°C pass, <60°C fail). Choice C is correct because it appropriately makes requirements testable with specific measurable values (at least 60°C at 12:00 PM after 5 hours). Choice A is vague ('very hot and delicious'); Choice B is vague ('hot enough'); Choice D treats constraints as optional or ignores them (expensive contradicts budget). Establishing clear design requirements is essential: make criteria testable for objective judgment. The specificity helps guide and evaluate designs. - A lab transport device must keep samples between 2∘C and 6∘C for 8 hours and hold 200 mL. Constraints: $100 budget, insulated, shock-resistant, and it must include temperature monitoring.
Which revised requirement is the BEST example of making a vague idea into a measurable criterion?
Answer: The container must keep the samples between 2∘C and 6∘C for 8 hours.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—specific goals like 2-6°C for 8 hours, hold 200 mL; (2) constraints—$100 budget, insulated. The best revision turns vague ideas (e.g., 'cold') into measurable ones with numbers and tests (e.g., temperature range over time). Choice C is correct because it changes vague 'keep cold' to specific 'between 2-6°C for 8 hours' (measurable with thermometer). Choice A remains vague ('cold'); choice B is subjective ('high quality'); choice D is vague ('best material'). Establishing clear design requirements is the essential first step in engineering design process: specific criteria enable objective verification and improvement. - Design challenge (Hot lunch container): Keep 500mL of soup at ≥60∘C for 5 hours. Constraints: cost under $20, height ≤15cm, safe exterior (no burn risk), and materials limited to plastic/foam/metal.
Which item below correctly matches a criterion with the tool you would use to test it?
Answer: Soup stays ≥60∘C at noon — thermometer
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). To test requirements, you must match each requirement with appropriate measurement tools—criteria need tools that measure performance (thermometer for temperature, timer for duration, scale for mass), while constraints need tools that verify limits (ruler for dimensions, calculator for cost, material specifications for safety). For this hot lunch container: Criteria include maintaining ≥60°C (needs thermometer to measure temperature), working for 5 hours (needs timer/clock to measure duration), holding 500 mL (needs measuring cup to verify volume), and safe exterior (needs touch test or surface thermometer). Constraints include cost under $20 (needs cost calculation adding components), height ≤15 cm (needs ruler to measure dimension), and specified materials (needs visual inspection or material list). Choice C is correct because it correctly matches a criterion with the tool to test it (soup stays ≥60°C at noon is a temperature criterion—thermometer measures temperature to verify if ≥60°C threshold is met after 5 hours). Choice A incorrectly matches constraint with wrong tool (cost under $20 is a constraint not criterion, and thermometer doesn't measure cost—need calculator/receipts), Choice B matches constraint with wrong tool (height ≤15 cm is a constraint not criterion, and stopwatch doesn't measure height—need ruler), and Choice D matches constraint with wrong tool (material limitation is a constraint not criterion, and measuring cup doesn't verify materials—need visual inspection). Proper testing requires: identifying what type of requirement it is (criterion = performance goal, constraint = limitation), selecting appropriate measurement tool (temperature → thermometer, dimension → ruler, cost → calculator), establishing test procedure (when/how to measure), and recording results to compare against requirement (62°C measured > 60°C required = pass). - Hot lunch container design challenge: Keep 500 mL of soup at or above 60°C for 5 hours (7 AM to noon). Constraints: cost under $20, height ≤ 15 cm, safe exterior (no burn risk), and materials limited to plastic, foam, metal.
A student writes this requirement: "The soup should stay warm for a long time."
Which revision makes this requirement a testable criterion?
Answer: The soup should stay at or above 60°C for at least 5 hours.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: maintain ≥60°C temperature, work for 5 hours duration, hold 500 mL capacity), which are measurable targets that testing will verify (thermometer measures if temp ≥60°C met, timer measures if 5 hour duration met); and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: cost under $20 budget, height ≤15 cm to fit backpack, safe exterior preventing burns, materials limited to plastic/foam/metal). The original requirement "The soup should stay warm for a long time" is too vague to be testable: "warm" is subjective (40°C? 50°C? 70°C?—different people have different definitions), "long time" is undefined (2 hours? 8 hours? all day?), there's no clear pass/fail threshold (how warm is warm enough?), and testing would be ambiguous (one person says "warm enough," another disagrees). To make criteria testable, you need specific measurable values: temperature in degrees (°C or °F), time in hours/minutes, volume in mL or liters, and other quantifiable parameters that instruments can measure objectively. Choice B is correct because it makes the requirement testable with specific measurable values: "at or above 60°C" gives exact temperature threshold (measure with thermometer: 60°C or higher = pass, below 60°C = fail), and "for at least 5 hours" gives exact time duration (use timer: if still ≥60°C at 5 hours = pass, if drops below before 5 hours = fail). Choice A remains vague with "warm" (not specific temperature) and "tasty" (subjective, not measurable); Choice C focuses on material choice (metal) which is a design decision, not a performance criterion; Choice D addresses affordability which is a constraint (cost limit), not a performance criterion. Making criteria testable enables objective evaluation: everyone knows exactly what to achieve (≥60°C, not subjective "warm enough"), testing is unambiguous (thermometer gives number, compare to requirement), improvement targets are clear (if achieved 55°C, need 5°C improvement—know exactly how much better needed), and different designs can be compared fairly (Design A maintains 65°C, Design B maintains 58°C—A clearly better). The specificity helps guide design decisions: need ≥60°C for 5 hours leads to calculating required insulation thickness, selecting materials with appropriate thermal properties, and potentially adding features like preheating or phase-change materials.
- Design challenge (cold drink cooler): You are designing a cooler for an outdoor event that lasts 4 hours on a 30∘C day. Goal: keep drinks cold. Criteria: keep drinks at ≤10∘C for 4 hours and hold 12 standard cans. Constraints: budget $50, must be portable (handles or wheels), durable for repeated use, and you may use foam, plastic, and ice/ice packs.
Which option lists the constraints (limits) for this design?
Answer: Budget $50; must be portable; must be durable; materials limited to foam, plastic, and ice/ice packs
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: keep drinks at ≤10°C temperature, work for 4 hours duration, hold 12 cans capacity), which are measurable targets that testing will verify (thermometer measures if temp ≤10°C met, timer measures if 4 hour duration met, count cans to verify capacity); and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: budget $50 maximum, must be portable with handles/wheels, must be durable for repeated use, materials limited to foam/plastic and ice/ice packs), which bound the solution space preventing unlimited resources or unrealistic designs. For this cold drink cooler: The constraints (limitations) are: (1) budget $50 (cost constraint: maximum spending limit, eliminates expensive commercial coolers perhaps, testable by adding component costs), (2) must be portable (mobility constraint: needs handles or wheels for transport, testable by attempting to carry/move), (3) must be durable (longevity constraint: withstand repeated use not single-use, testable through multiple use cycles), and (4) materials limited to foam, plastic, and ice/ice packs (resource constraint: can't use exotic materials or electric cooling, limits design choices). Choice C is correct because it accurately identifies constraints as limitations (budget $50, must be portable, must be durable, materials limited to foam/plastic and ice/ice packs—all boundaries to work within). Choice A lists criteria not constraints (temperature ≤10°C, hold 12 cans, last 4 hours are all performance goals to achieve), Choice B describes testing methods not requirements, and Choice D mixes criteria with vague statements ("cold and refreshing" isn't measurable). The distinction is clear: criteria describe what the device must DO (maintain temp, hold volume, work for time), while constraints describe what you must work WITHIN (cost limit, portability requirement, material restrictions)—criteria are achievements, constraints are boundaries. Establishing clear requirements helps guide design decisions: constraints eliminate certain approaches (can't use $200 commercial cooler due to budget, can't use dry ice due to material limits), while criteria set clear targets to achieve through testing.
- Ice cream transport design challenge: You need a container to transport 1 liter of ice cream from the store to home in 30 minutes without melting. The ice cream must stay at or below -5°C. The container must cost under $15, be portable (easy to carry), not leak, and be made from food-grade safe materials.
Which statement correctly distinguishes criteria from constraints for this design?
Answer: Criteria describe what the design must accomplish (like staying at or below -5°C for 30 minutes and holding 1 liter), while constraints describe limits (like under $15 and food-grade materials).
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: maintain ≤-5°C temperature for frozen ice cream, work for 30 minutes duration, hold 1 liter capacity, prevent leaking), which are measurable targets that testing will verify (thermometer measures if temp ≤-5°C met, timer measures if 30 minute duration met, measuring cup verifies 1 liter fits, visual inspection confirms no leaks); and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: cost under $15 budget, must be portable/carriable, materials must be food-grade safe), which bound the solution space preventing unlimited resources or unsafe designs. For this ice cream transport: The criteria (performance goals) are: (1) maintain ≤-5°C (temperature criterion: ice cream must stay frozen solid, -5°C ensures no melting, testable with thermometer after 30 minutes), (2) duration of 30 minutes (time criterion: store to home transport time, must stay frozen this long, testable with timer), (3) capacity 1 liter (volume criterion: must hold family-sized container, testable with measuring), and (4) no leaking (functional criterion: melted ice cream must not escape, testable by inspection). The constraints (limitations) are: (1) cost under $15 (budget constraint: affordable for regular shopping, testable by adding costs), (2) portable/easy to carry (usability constraint: one person can transport while carrying groceries, testable by carrying), and (3) food-grade safe materials (safety constraint: materials must not contaminate food, verified by material specifications). Choice B is correct because it properly distinguishes criteria from constraints (goals vs limits): criteria describe what the design must accomplish (staying ≤-5°C for 30 minutes and holding 1 liter are performance goals), while constraints describe limits (under $15 and food-grade materials are boundaries to work within). Choice A confuses criteria and constraints: incorrectly labels cost as criterion when it's a constraint (limit, not performance goal), and temperature as constraint when it's criterion (goal to achieve); Choice C incorrectly states they are the same thing when they serve different purposes; Choice D makes false generalizations that criteria are only about materials and constraints only about temperature, which is completely incorrect. The distinction is fundamental to engineering design: criteria are what you're trying to achieve (keep ice cream frozen at ≤-5°C), constraints are what limits how you achieve it (must cost under $15, use safe materials). Both are essential: criteria without constraints could be met with expensive exotic materials (not realistic), constraints without criteria leave unclear what to accomplish (insulated box but no temp target?—how to judge success?).
- Laboratory sample storage design challenge: You must transport biological samples to a lab and keep them at 4°C ± 2°C (must stay between 2°C and 6°C) for 8 hours. The container must hold 200 mL of samples, be insulated, include temperature monitoring, be shock-resistant, and stay within a $100 budget.
Which measurement plan best tests whether the temperature criterion is met?
Answer: Use a thermometer/data logger to record the internal temperature over 8 hours and confirm it stays between 2°C and 6°C.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: (1) criteria—the performance goals that define success (what the design must accomplish: maintain 4°C ± 2°C temperature meaning between 2°C and 6°C, work for 8 hours duration, hold 200 mL capacity, include temperature monitoring capability), which are measurable targets that testing will verify (thermometer/data logger measures if temp stays within 2-6°C range, timer measures if 8 hour duration met, graduated cylinder verifies 200 mL fits); and (2) constraints—the limitations that restrict how you can achieve the criteria (what you must work within: cost under $100 budget, must be shock-resistant for transport, must have insulation, must include monitoring equipment), which bound the solution space ensuring practical and safe design. For laboratory sample storage, the most critical criterion is maintaining precise temperature control: biological samples are extremely temperature-sensitive, and the narrow range of 2°C to 6°C (4°C ± 2°C) must be maintained continuously for 8 hours to preserve sample integrity—even brief excursions outside this range could damage samples, making this the primary performance goal that must be tested rigorously. To make this criterion testable: use a calibrated thermometer or data logger to record internal temperature continuously or at regular intervals (every 15-30 minutes), document the temperature profile over the full 8 hours, verify all readings stay within 2°C to 6°C range (any reading outside = failure), and calculate statistics like average temperature and maximum deviation to ensure consistent performance. Choice C is correct because it uses a thermometer/data logger to record the internal temperature over 8 hours and confirm it stays between 2°C and 6°C—this directly measures whether the temperature criterion is met with objective data. Choice A (weighing the container) doesn't measure temperature at all and weight change is irrelevant to temperature control; Choice B (feels cold to touch) is subjective and imprecise—"cold" could mean 10°C or 0°C, and external feel doesn't indicate internal temperature; Choice D (timing construction) measures build time not temperature performance. Establishing clear design requirements with testable criteria is essential: the specific temperature range (2-6°C) makes testing unambiguous—either the temperature stays within range (pass) or it doesn't (fail), with no subjective interpretation. The measurement plan must match the criterion being tested: for temperature criteria, use temperature measurement tools (thermometers, data loggers); for volume criteria, use volume measurement (graduated cylinders); for time criteria, use timers—the tool must measure the same parameter as the criterion specifies.
- Design challenge (cold drink cooler): Keep 12 standard cans at ≤10∘C for 4 hours outside on a 30∘C day. Constraints: budget $50, portable (handles or wheels), durable, materials limited to foam/plastic and ice/ice packs.
Which requirement below is a constraint, not a criterion?
Answer: The cooler must cost $50 or less.
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Design requirements have two components: criteria describe what the device must DO (maintain temp, hold volume, work for time), while constraints describe what you must work WITHIN (cost limit, size limit, material limit)—criteria are achievements, constraints are boundaries. For the cold drink cooler challenge, we must distinguish between performance goals the cooler must achieve (criteria) and limitations on how we can achieve them (constraints). The criteria are: keep drinks at ≤10°C (temperature performance), hold 12 standard cans (capacity performance), and work for 4 hours (duration performance)—all describe what the cooler must accomplish. Choice D is correct because it identifies a constraint, not a criterion: the cooler must cost $50 or less is a budget limitation (constraint) that restricts how you can achieve the performance goals, not a performance goal itself. Choices A, B, and C all describe criteria (performance goals): keeping drinks at ≤10°C is the temperature criterion, holding 12 cans is the capacity criterion, and working for 4 hours is the duration criterion—these define what the cooler must DO to succeed. The distinction matters for design: criteria tell you what to achieve (cold drinks for the party), constraints tell you the boundaries for achieving it (can't spend unlimited money). A $200 commercial cooler might easily meet all criteria but violates the cost constraint; a $10 foam box might meet the cost constraint but fail the temperature criterion. Both criteria and constraints must be satisfied for successful design. Understanding this distinction helps in design process: first identify what must be accomplished (criteria set the targets), then identify limitations (constraints bound the solution space), design within constraints to meet criteria, and test against criteria while confirming constraints aren't violated.
- Design challenge (Ice cream transport): Hold 1L of ice cream and keep it at or below −5∘C for 30 minutes. Constraints: cost under $15, portable, no leaks, food-safe materials.
Which set of requirements includes all the key measurable criteria needed to judge success?
Answer: Keep temperature ≤−5∘C for 30 minutes; hold 1L; does not leak (safety/quality requirement)
This question tests understanding of how to establish design requirements by setting criteria (measurable performance goals the design must achieve) and constraints (limitations the design must work within). Complete design requirements must include all key measurable criteria that define success—missing any critical criterion means you cannot fully evaluate if the design succeeds (like trying to judge a race without knowing the finish line). For ice cream transport, the key criteria are: (1) temperature maintenance ≤-5°C (primary function: keep ice cream frozen), (2) duration of 30 minutes (time requirement: store to home), (3) capacity of 1 L (volume requirement: hold the ice cream), and (4) no leaking (quality/safety requirement: prevent mess and product loss). These are all measurable: thermometer verifies ≤-5°C, timer confirms 30 minutes, measuring cup checks 1 L capacity, and visual inspection confirms no leaks. Choice C is correct because it includes all the key measurable criteria needed to judge success (keep temperature ≤-5°C for 30 minutes—combines temperature and time criteria; hold 1 L—capacity criterion; does not leak—safety/quality criterion; all are specific, measurable, and together fully define successful performance). Choice A lists vague unmeasurable terms ("portable" and "looks nice" are subjective, "keeps ice cream cold" lacks specific temperature), Choice B lists only constraints not criteria (cost limit, food-safety, and portability are all limitations not performance goals), and Choice D lists design specifications not criteria (specifying exact materials and lid type constrains design choices but doesn't define what to achieve). Complete criteria enable comprehensive evaluation: test each criterion systematically (temperature after 30 min: -7°C ✓, volume held: 1 L ✓, leaking observed: none ✓), confirm all criteria met for success (missing any = failure), distinguish from partial success (3 of 4 criteria met still means design needs improvement), and guide design improvements (if temperature was -3°C, focus on better insulation).
