Engineering Mindset #4: Criteria and Constraints
If you’ve tried to solve a problem, or teach problem solving skills in a blue sky sort of format you are likely familiar with the expanse of the human imagination. Let’s consider something small like, you’ve got the day off. You just got up from a nap and everyone you know is at work or school and busy and it’s pouring rain. What should you do? Well you can just turn on the TV. Whatever comes on solves the problem, because now you’re watching TV! So entertaining, right?
What happens to be on is a test pattern with a loud continuous beeping behind it. Are you not entertained? Well, probably not. So you decide to watch something else. And you flip channels. The next channel is in a language you don’t speak then the next channel is in black and white, not your thing. The next channel is showing news and another flip to tiny puppets talking to a dog? A couple of flip more show an old sports game in another language and a sitcom you’ve never seen before. Hmm, maybe. Next the middle of some movie, very dramatic but it’s the middle. Next. This is one option.
(Can you believe all TV used to be like this?) Looking at what’s on each channel available to you. One by one until something catches your eye. Having to watch whatever comes on when it’s on. But back to our topic…
But HOW are you deciding what you want to watch?
To get to something you want to watch you start with some criteria: You’re in the mood to laugh. (story type/materials) You’ve got a couple hours before you need to do something else (size/time). You’ve had a nap so you’re not really tired so you’re open to watching something requiring attention. (efficiency) These are things that the show MUST have to be worth choosing.
But, you’ve got to make dinner later because you’ve got friends coming by for dinner at 7 and it’s 2:40 now. So you’ll need at least two hours to get ready and cook; you’ll need to start that by 5:30. So the show must be on between now and 5:30 (time). And you definitely don’t want to be left hanging about how it might end (size/duration)! It’s got to catch your attention (topic/materials), no test patterns or languages you don’t speak for you. And no subtitles, you lost your glasses last week and you won’t get the new ones until tomorrow. Those become your constraints.
The original plan to flip channels could work, but you also like to know you’re picking the BEST option available because, after all, you’re paying for it. So you turn to the ‘what’s on’ channel and start looking for stuff that will be starting soon and be done by 5:30 to watch and might make you laugh, but will definitely be engrossing. So now you have two potential solutions that meet your criteria and constraints to find the best show to watch.
There you go!!! Surprise! That’s how criteria and constraints work in the engineering design process too. Want to watch a video?
This video from KQED discusses how engineers and scientists figured out how to bring deep water fish into an aquarium…as usual there are many details…like fish from one environment needing to go into their own unique environment or they would die. The lesson plan that accompanies on exploring how to identify criteria and contraints can be found here.https://media.nationalgeographic.org/assets/file/4-_Identify_Criteria_and_Constraints.pdf .
For more information here is a blog from a teach exploring this in greater detail https://sites.google.com/site/korbinsportfolio/lessons/criteria-and-constraints
This video for older learners outlines the ideas in a bit more detail as an introduction to the concept.https://www.youtube.com/watch?v=CcIt6_pB1lg
This article from STEM Teaching Tools explores ways to support students on how they can think about and understand criteria and constraints themselves as part of the engineering design process.http://stemteachingtools.org/brief/64
Constraints often sound negative, but this Ted Talk is a great way to consider how constraints are necessary and work not just in engineering but in a variety of fields.https://youtu.be/v5FL9VTBZzQ