My first job in Saskatoon was as a sessional instructor for a 3rd year rock mechanics class in Engineering. I was waiting to defend my thesis and this was the perfect part-time gig to keep me busy until I could complete my Master’s degree. I was horrified to see that Professor Doug Milne gave his students weekly quizzes on stress and force. But then I thought about it. These use equations all engineering students learn in 1st year (or before). This is fair game. Way to go Doug! The students need to appreciate that each class is building on the content of their other classes.
With this new insight, I bravely solved a set of Doug’s quizzes and definitely did not get them all correct. To be fair, it had been over 20 years since I did this type of calculation. But I won’t fib. I was cheating with the equations in front of me whereas the students don’t have that luxury. So it was really a trade-off between the students’ remembering the math because they use it in other classes, and me needing the unit conversions. Most everyone makes errors on these.
I had my ah-ha moment with the math, and that is where I learned about the term threshold concepts in learning. According to Meyer and Land (2003), this is “opening up a new and previously inaccessible way of thinking about something”. In our classes, we learn the equations and fill them in based on the course subject. Here we are using the math to apply to common everyday objects. And we mix up the units between imperial and metric. We are trying to get the students to estimate and realize when the units or quantities do not make any sense.
This term I had fun while making a new set of quizzes. Here is one quiz I made up this term. What is the stress under one of the horse hooves? And under all four? Stress is just force divided by area. I know that some students will be horrified by this experience like I was at first. That is why I made up a video to explain the equations and posted it here (Introduction to Calculating Stress for Rock Mechanics). I did a lot of thinking and came up with my own way of interpreting the equations. I post it so students can reflect on the equations in a different way. I hope it helps some of them. I got to figuring this out so they definitely can too.