The NGSS Science and Engineering Practice of Asking Questions and Defining Problems asks students to identify the criteria and constraints presented by a given problem. Criteria and constraints are both aspects of a problem that limit a solution. Students should be started to identify these components starting in 3rd grade.
Criteria & NGSS
Part of the engineering design process is defining problems in detail. This includes listing the requirements of the solution. The criteria are a list of needs that the solution must be designed to meet.
Here’s an example problem. Let’s say I would like to redesign my backyard. I would love to have a pool and a hot tub added to the backyard and still have enough room for an outdoor garden.
In this example, the criteria are the pool, hot tub, and garden space.
Constraints are factors that limit the possible solutions.
In the scenario above, there are a lot of potential constraints. For example, I have a tiny backyard that is common in California in houses that have been built in the last 20 years. It is probably 40 feet wide, but only about 15 feet across. This makes it nearly impossible to build all of the things I want in my backyard.
Cost is one of the most common constraints that is presented in a problem. Let’s say that I have only saved $10,000 for my backyard renovation. While that’s a good start, it will be difficult to build a pool on that kind of budget.
Students may also be asked to look at the type and availability of the material that will be used for the design solution. Time is another commonly used constraint.
When looking at my backyard design problem, there is unlikely to be a solution that meets all of the criteria because the constraints limit the solution. I might be able to upgrade my garden area and add a hot tub to the yard. However, a pool is likely too expensive and will take up to much space.
Progression Across Grade Levels
Students are asked to deal with limitations and fulfill a list of requirements as early as third grade and through fifth grade.
In middle school, students are asked to identify the criteria and constraints and provide as much information about each of them as possible. They are also required to consider scientific principles that might limit a possible solution.
In high school, students are also asked to consider societal norms and risk mitigation when listing requirements and limitations. Students are also asked to consider problems that occur at both the local and global levels.
Are you looking for ways to teach your students to define problems?
Check out this resource that I have available on my Teachers Pay Teacher store. It provides students with 4 scenarios and a graphic organizer.
It is a quick way to introduce your students to the practice of Defining Problems.
Here are some other resources that you might want to take a look at: