Balance Criteria and Constraints
Engineers must meet the designated criteria for success and client preferences while staying within specified constraints. They need to make tradeoffs among parameters such as cost, performance, materials, time, ethics, and sustainability.
Why is balancing criteria and constraints important for youth?
Balancing criteria and constraints helps youth approach engineering with a clear understanding of the problem and what success looks like. By identifying and revisiting these parameters, students learn to evaluate ideas, make thoughtful tradeoffs, and improve designs within real-world limits like time, materials, and cost. This practice builds critical thinking and decision-making skills, as youth recognize that no solution can optimize every factor, and instead work to design the best possible solution within given constraints.
How does YES support balancing criteria and constraints?
Builds understanding developmentally.
In YES units, younger students focus on what their design “needs” to do (criteria), while constraints are embedded through limits on materials and time. By upper elementary, constraints are explicitly introduced, and in middle school, students help define criteria based on user needs and context.
Makes criteria and constraints clear and visible.
Students co-construct and revisit a class design requirements chart, helping them track criteria and evaluate ideas throughout the design process.
Engages students in tradeoffs.
Across YES challenges, students must prioritize competing goals. For example, when designing a medicine cooler, students decide whether to prioritize carrying more medicine, keeping costs low, or keeping medicine coolest, and learn that engineers balance criteria and constraints to develop the best possible solution.
Videos
View this classroom video of students balancing criteria and constraints.
I Forgot About the Cold Pack!
What Does Our Hat Needs to Cover?
Video Reflection Questions
Other Resources
Engineer It, Learn It: Science and Engineering Practices in Action by Cathy P. Lachapelle, Kristin Sargianis, and Christine M. Cunningham in Science and Children – November 2013
What does balancing criteria and constraints look like in your classroom?
- Encourage creative problem-solving: Remind students that constraints don’t limit creativity; they inspire it! Challenge them to think of multiple ways to meet the criteria.
- Model real-world trade-offs: Share examples like space missions to show how engineers balance limits such as weight or cost.
- Use discussion and reflection: Ask students to explain how their design choices balance criteria and constraints. What trade-offs did they make?
“[The students] were definitely in this mode of, okay, we have a task to do. We need to solve this problem. There are these constraints. But we need to figure this out. And then they went out and did it.”
- 5th grade teacher
In real-world engineering, every design must meet criteria and constraints—from safe bridges to affordable medical devices. A study by the National Academy of Engineering found that engineers spend up to 70% of their time refining designs to meet constraints like cost, safety, and sustainability.