Engineering Practice: 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.

“I Forgot About the Cold Pack!”

Middle school students work through the budget for their medicine cooler, considering the materials it will be made from, the amount of potassium chloride they will use as a cooling agent, and how many medicine bottles it can hold. Watch & Reflect:

Reflection Questions

  1. How are you balancing your budget?
  2. Which of the criteria did your group decide was most important to design for? How did prioritizing that criterion impact your overall design?
  3. Who might not be able to use your medicine cooler?
  1. In early elementary school, students may have a list of available materials and quantities as constraints rather than a budget. Criteria can be simplified. For example, in the Engineering Pumpkin Pollinators unit, students are given the following criteria: the hand pollinator needs to fit inside the flowers, pick up pollen from one flower, and drop off pollen at another flower. These simple directives make this practice accessible to young learners but can be built upon as they grow.
  2. Some ways we can scaffold this practice with young learners are to:
    a.  Physically model the criterion to show students what it means to “fit inside the flower.”
    b.  Post the criteria in the room.
    c.  Use graphics and images to support all students in recalling the criteria and constraints, regardless of their reading skills.
    d.  Review the criteria and constraints throughout the lesson and unit to help students remember what their design needs to do.