Students who demonstrate understanding can: Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
Official wording from the Next Generation Science Standards (NGSS Lead States, 2013). NGSS is a registered trademark of WestEd. Neither WestEd nor the lead states and partners that developed the NGSS were involved in the production of this page, and they do not endorse it. View on nextgenscience.org
Engineers rarely fail because they cannot build something; they fail because they built the wrong thing. Before sketching a single idea, students learn to pin down exactly what a successful solution must do (the criteria) and the limits it must work within (the constraints), written precisely enough that anyone could test whether a design meets them.
Criteria are measurable goals: a cooler must keep ice frozen for at least 3 hours, a bridge must hold 500 grams. Constraints are restrictions: a budget of 10 dollars, only the materials provided, a size that fits on a desk, a 2-day build time. Vague statements such as "it should be strong" or "it should not cost too much" cannot be tested. Students also bring in relevant science, such as how insulation slows thermal energy transfer, and think about effects on people and the environment that might rule some solutions out, like materials that cannot be recycled.
A well-defined problem saves time later, because it gives a clear way to compare designs and decide when one is good enough.
Criteria describe what the solution must achieve; constraints describe limits like cost, time and materials. Sorting examples into two columns helps.
A criterion must be measurable, such as holding 2 kilograms for 30 seconds, so a test can show whether it was met.
Constraints also include time, size, available materials, safety rules and environmental effects.
Skipping this step leads to designs that solve the wrong problem or cannot be fairly compared.
Students are asked to design a lunch cooler. Write precise criteria and constraints for the problem.
Answer: The cooler must keep 100 grams of ice at least half frozen for 4 hours and fit a 20 by 15 by 8 centimeter box, using under 5 dollars of supplied materials within two periods, with reusable or recyclable materials preferred.
Give groups a deliberately vague brief, such as "design a better pencil holder", and ask them to turn it into testable criteria and constraints before any building. Comparing different groups' statements shows why precision matters. Revisit the criteria at the end to judge final designs.
Assessment items often ask students to classify statements as criteria or constraints, or to improve a vague criterion so it can be measured.
Original questions written for this standard. Choose an option or type your answer, then press Check. Every question has a worked explanation.
Answer: A) It must hold 500 grams
A criterion describes what success looks like; holding 500 grams is a measurable goal. The others are constraints.
Answer: D) The budget is 10 dollars
A budget is a limit on the solution, which makes it a constraint.
Answer: C) The boat must float while holding 20 pennies for 1 minute
It states a measurable load and time, so a test can check it.
Answer: constraint (also accepted: constraints, a constraint)
Constraints are limits that the solution must work within.
Answer: A) They might rule out some solutions
Harmful environmental effects can make a solution unacceptable, so they shape the constraints.
Answer: criteria (also accepted: criterion, the criteria)
Criteria are the measurable goals that define success.
Analyze a major global challenge to specify qualitative and quantitative criteria and constraints for solutions that account for societal needs and wants.
A full lesson with slides, activities and an exit ticket on defining criteria and constraints, pitched to grades 6-8 and editable in PowerPoint or Google Slides.
Make a lesson βA printable, differentiated worksheet on MS-ETS1-1 with an answer key, ready in about a minute.
Make a worksheet βTurn defining criteria and constraints into a quiz students answer online that marks itself, with a class summary for you.
Build a test βCriteria are what a successful solution must do; constraints are limits such as cost, time, materials and size.
Yes. Students take into account relevant scientific principles and possible impacts on people and the environment.