Emphasizing concepts: Memorization is one of them

I know there is an algebra requirement for this course, but, how much/which algebra do I need ?
(Question asked of me by a number of students enrolling in introductory college physics)

Of course it’s not just about memorization. Of course memorizing formulae will not help, if one does not know when and how to apply them. But the fact that it is not all about memorization does not mean that no memorization should be required. One cannot learn physics without memorizing anything at all. Anyone who claims to be able to teach physics (or anything else) without any memorization is almost certainly a quack.

There is no way to “figure out”, say, Coulomb’s law by “intuition”, or reasoning. And without knowing it, one cannot do electrostatics. Simple as that.
And you know what ? It’s the same in all other disciplines. Very few people can play music without being able to read it, speak a foreign language without memorizing verbs and grammar, act in a play without memorizing the lines, drive a car without memorizing the meaning of those road signs. And while all of these activities amount to much more than just memorization, memorization is a necessary part. “Rote memorization”, that’s right, the expression that makes many a modern educator go “eew”, give a grimace of disgust upon pronouncing it. Well, I am sorry, but it is high time we go back to recognizing “rote memorization” as a respectable component of learning [0]. Component is the keyword here.

“But I can always look it up ! There is Wikipedia, you know…”, tell me many a student.
Nonsense. First off, if one needs to use it frequently, at some point it will be retained by heart, much like an ESL speaker does not need to look up the past tense of an English verb, after the first three times (s)he has said “writed” and been corrected by a native speaker. Students who have supposedly worked through hundreds of homework problems, all making use of Coulomb’s law, or repeatedly utilizing concepts like Work, or Energy and Momentum conservation, who claim “not to remember them”, must have had someone else do the homework for them.
Secondly, while “looking up” the most complicated formulae, which require lengthy and nontrivial derivations (especially those that are only needed once in a while) is obviously accepted and fully understood, there is a point where having to resort to a manual, textbook or “cheat sheet” to solve even the simplest problems, or a calculator for performing the most elementary operations, points to one’s poor understanding and even limited thinking ability, casting serious doubts about the person’s future professional effectiveness.

So ingrained is the notion that nothing, nothing should be memorized, that students will often think that something is too difficult for them, that “they are not getting it”, when in reality they are simply not studying it. While concepts like Mass, Energy, Momentum and their implications, are subtle and quite profound, and are fully understood only with time, after spending many hours thinking about them, their definitions and use in the simplest problems of Mechanics are straightforward, and for the most part require little more than memorization.

So, when you, student, ask me for help with a problem having to do with, say, kinetic energy, and I say to you “OK, let us start from the beginning: what is the definition of kinetic energy ?”, please don’t look at me like I have asked you to hand me your credit card, and don’t give me this nonsense “Oh, I don’t understand that… concept“.
There is nothing to understand here; what you really should be saying is “Oh, I have not bothered to study”. You see, I am sure you have your valid reasons but the the problem is, you cannot solve any problem having to do with kinetic energy (or anything else) if you don’t even know what kinetic energy is in the first place. And that, I am sorry, you are going to need to memorize.
If you are not going to take the time to study your textbook, or at least your notes, it is going to be pretty impossible for me to help you, and pretty useless for you to be enrolled in the course in the first place.
But it’s not like I am pissed about it, or anything… not at all.


[0] See, for instance, D. Rehfuss, The Physics Teacher 38, 120 (2000).

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6 Responses to “Emphasizing concepts: Memorization is one of them”

  1. Anonymous Says:

    Reading posts like yours makes me so glad I am not involved in any teaching of any kind… (sorry).

    Of course some teachers rely on memorisation far too much. We had a physics teacher in high school who would get quite frustrated when we would ask “but why?”, and would say “you don’t really need to understand why, as long as you can give the right answer in your exam” (yes, for real, and people wonder why I dropped physics as soon as I could, i.e. at 16. Did I mention that this teacher was also a good friend of my Dad’s?). Anyway. He also complained that it was always the girls who wanted to know why, whereas the boys were content just to write it down and remember it. I always learn and remember things better if I know the reasons behind them!

    Oh, and clearly my physics memory is terrible… I thought Coulomb’s law was that one describing current / magnetic field / movement. You know, the one that makes whole classrooms of students look like they are throwing gang signs as they try to answer their exam questions.


    • Massimo (formerly known as Okham) Says:

      Why does gravitation work like that ?

      “It is an experimental fact. Laboratory measurements are consistent with this law, and that is what physics is based on. From this fundamental law one can make a number of accurate predictions that are of crucial importance in many areas of science.
      Nobody has yet been able to understand what, at the most fundamental level, underlies this physical behavior. This is perhaps the most advanced topic of study in current physics and, who knows, maybe one of you will help explain it, some day.”

      This is what I would answer, if any student ever asked me this question in class (I am not holding my breath though — for the most part they could not care less, really — men or women).

      I thought Coulomb’s law was that one describing current / magnetic field / movement.

      LOL, I think you mean (maybe) this one… all I know is whenever I teach it students start giving me the middle finger… πŸ™‚

      • Anonymous Says:


        Oh my God, I used to teach for the SAT, and it was always shocking to me how much my students relied on their calculators for the simplest things. Literally, I had students who would reach for the calculator to figure out what 6 times 7 is, or what 1/4 of 4 was. I understand the argument that in the real world you have access to calculators or formulas or whatever, but that’s not exactly true. The real world often requires thinking on your feet. For example, I tend to be the “tip guru” among friends simply because I can calculate 20% tip faster than most people can pull out their cell phone, go to the calculator application, type out the numbers, and get the result. I mean 20% tip isn’t hard to figure out, and everyone assumes I’m really good at math. But it’s really just that I memorized my two times table long ago…. πŸ˜‰

      • Anonymous Says:


        forgot to add my name to my comment-

        ruchi aka arduous

        why does open id hate me?

  2. Anonymous Says:


    I am not sure if you have blogged about this before, but what do you think of the Canadian pre-college education quality? I always thought it is probably a match for the Scandinavian levels (social justice standards in Canada are much more humane than those in its southern neighbor), but your stories gives an image that is more American.

    • Massimo (formerly known as Okham) Says:

      Re: Zodia

      I do not know how representative of Canada as a whole is the place where I live, but having taught at the college level in the US for six years before moving here, the freshman scene is very similar. What strikes me is not so much what students do not know, but the extreme mental rigidity that they have acquired in high school. They have learned to do things in one way, and cannot conceive of doing it in any other.
      For example, I am struggling to get them used to work out physics problems using letters in their algebra, as opposed to plugging in the numbers right away, something that they do almost as a Pavlovian reflex.

      And they seem unable to establish connections between, say, algebra and physics — in their mind they are separate, and it is almost shocking to them that there is so much algebra to do in physics (the tendency is to think that I, the instructor, am choosing to make it so algebra-heavy.

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