Teaching Success
Last semester, during the very last lab, one of my students asked me "What are the units of velocity?". She was, otherwise, a great student; however, after ten labs and a semester of lecture she didn't know the units of velocity, and even worse she didn't know how to figure this out when given the equation used to calculate velocity. The even bigger problem is that this is not a unique or isolated incident. This same student, and several others, throughout the entire semester will ask me to spell out the units for various quantities even though they are given everything needed to figure it out themselves. I realized that this problem was not unique to that semester or even to my lab sections. Other TAs have the exact same problem, and nobody can figure out how to get our students to learn units. This is amazing because finding the units of a quantity is very simple if you have that quantitys equation; it boils down to simple multiplication and division.
This bothered me a great deal, and so over winter break I thought a great deal about how I could get my students to learn units. I have tested out my plan so far this semester, and it so far it seems to be working. My plan has three parts: i) On the first day we typically only go over the syllabus, so we have plenty of time before class time ends and so I used that time for a lecture where I went over all the basics of units. ii) I give my students an online quiz every week to complete in Canvas. One of the primary tasks of the quizzes is to force them to practice finding and working with units. iii) I now have a very strict but simple grading standard for units. My policy is that units go everywhere. The first time a student makes a mistake with units I subtract 5% of their total lab grade, and if they make more than one mistake with units I subtract 10% of their total lab grade. So far, I have found that by being very strict and harsh with their grade the students will pay much more attention to the units. Even though the penalty is high, it appears to me that students lose fewer points due to units on average when compared to the old system of grading.