Practice Makes Perfect
Once again, I am teaching the Introductory Physics summer course, and this year I decided to add some extra practice exercises online for the students. These will be not for credit, but can be taken as many times as the student wants. The questions are chosen randomly from a pool of questions, and have semi-random values in them (within certain sensible ranges), so the student is very unlikely to be asked the same thing twice, and if they are, the answer will be different at each attempt. My idea here is to give students the chance to practice as much as they think necessary, before attempting an assignment which does count towards the final grade. In this first iteration, I’m not making it mandatory for students to do these exercises, and it will be interesting at the end of the course to evaluate how useful this is. I suspect that the students who most need the practice will probably be the ones least likely to do the practice tests. But we will see. I have been wrong before.
The reason why I want to this testing comes from my recent experience with marking a final exam. Units in the standard metric measurement system (SI) can be modified by adding a letter prefix, which acts as a multiplier. An example of this would be a centimetre (or centimeter if you use the US spelling) is one-hundredth of a metre (meter). The unit symbol for centimetre is cm, the “c” prefix modifying the symbol for metre, “m”.
The students had been given an electrical circuit, with a resistance given in MΩ (that’s mega-ohms — 1 million ohms). It turned out that many students did not know that the unit prefix “M” stands for million, so we had answers calculated using values from kilo-ohms (kΩ, 1000 ohms), milliohms (mΩ, one thousandth of an ohm) and micro-ohms (µohms, a millionth of an ohm). Knowing the letter prefixes for units is an essential skill for all scientists, no matter what the speciality. Naturally, depending on the discipline, some unit sizes are used more frequently than others, but for an introductory class, it is necessary to memorize these. Fluency in using the unit prefixes comes with practice, and so the first practice quiz was born. I would greatly prefer it if the students arrived from high school with this knowledge already memorized, but I have to acknowledge the reality of the situation, which is that many do not. Whenever I hear the phrase “They should already know this” uttered by a University teacher, particularly in respect to first year students, I now instantly respond with “Why do you make that assumption?”. For the high school intake from Ontario schools, some arrive extremely well prepared, others not so.
I’ve now extended the scope of the quizzes to include simple trigonometry testing, and splitting of vector quantities into components.
Again, these are things which are essential background tools for solving many physics problems, and the more practice the better. I will add other quizzes, as the term progresses. If they work well, they will be included into the syllabus for next year. The speed with which we have to cover material at University level means that more self-directed learning by the student is needed. Hopefully, these quizzes represent a little nudge along the right direction, and establish a framework to help direct the students’s learning experience.
