Exploring the Properties and Uses of Materials
Engineering Mindset #2: What’s it made of?
Our lives are filled with all sorts of lovely inventions that meet our needs with ease. We have lights, computers, tools to make projects easier. But how often do you pause to consider where they came from? And if a young person asks you–”where did this tool come from?” How would you answer? As an educator it’s key to be able to say, ‘hey, let’s think about that. Here’s how!’
Remember the video from last time? It discussed how you might engineer dinner working through the engineering design process, and trying to solve the problem of making dinner for yourself and a few friends without taking too much time. You may recall one of the suggested ideas – tortilla pb&j sandwiches? If you’re like me (and the video creators) you might agree it doesn’t sound good. But it’s a valid idea–if you can’t use bread and all you have are tortillas. Everyone in the story agreed it wasn’t very good. I’ll just use my imagination. But, it’s worth thinking about–why isn’t a tortilla a great replacement for bread in a pb&j sandwiches?
Let’s assume both your bread and your tortilla are made from wheat flour. Tortillas are kind of dry and thin and well, bread is thicker and spongy (porous) and traps moisture (absorbent) and is better to keep both the peanut butter and jelly in place. Maybe because it has flexibility and air holes that create space for the bread to expand and contract, and bread also has a crust. Crust is not very spongy or porous and creates a relatively solid, smooth, less flexible barrier that some might find similar to a tortilla in some ways, especially around the edges, while the middle part can fill and expand a bit more. Its texture is very different from the middle. It’s texture, which is sometimes left behind when the rest of the sandwich is gone, kind of reminds me of tortilla – a little.
I imagine you’d need a lot less jelly than you might prefer if you were using tortillas. Different properties make different materials better or worse suited for certain things. So while tortillas are great for burritos, they aren’t as good for a pb&j. Likewise, I’m not feeling very hungry thinking about a bean burrito made from a slice of bread instead of a tortilla. This blog from EiE talks about this in greater detail. https://blog.eie.org/investigating-materials-properties-is-an-engineering-habit-of-mind
And if you’re looking for something you can use to bring this topic to your students, check out the resources below.