Pedagogical metaphors are like a sober friend on your way out an especially good party. You can lean on him a bit. If he’s a good friend, you can lean a little more. Lean too much and you both fall in the gutter and he’s not gonna wanna party with you any more.
I was thinking about this as a medical professional gave a presentation on HIV awareness to my students this week. She came to a few of my class, and each time she made a point to tell us about macrophages, a kind of white blood cell that engulf and consume debris in our blood stream. Every time she got to this topic, she made a point to ask the students if they’d ever played Pacman.
This was a particularly dated metaphor, but oddly enough it seemed to work as almost all of the students had played this old game at some point in their lives. So, they got her point. Still I thought this an odd artifact of sorts. If it worked today, it must have worked so much better a couple decades back when Pacman was a common presence in just about everyone’s daily life. People might have walked by the machine back then (I did, right on to Asteroids), but they saw it, they knew it, and most had dropped a quarter or three in a Pacman at some point in their lives.

I want an Asteroids-themed lesson!
I couldn’t help wondering if this metaphor wasn’t more important to her own thinking than it was for the students. …if it wasn’t less a means of communicating with them than it was an essential crutch propping up her own approach to the topic. Then I remembered how much I love my soda wars (Coke and Pepsi) analogy when I talk about the Cold War. I know damned well the students don’t remember the cola wars. Most of them weren’t even alive when Pepsi set fire to Michael Jackson’s hair. But the metaphor just seems so perfect for me that I can’t resist using it, even if I have to teach the students about the cola wars in order to then use this to teach them about the cold war. (The punch line here, for those with enough morbid curiosity to damn a give, is that third parties were the real losers in the conflict). I use that metaphor a lot, but it’s probably more compulsive behavior than focused and well designed pedagogy. So, that’s at least one conceptual party-buddy that I’ve squashed on the curb in return for his patient efforts to guide my clumsy ass through a topic.
As to dated material, you can ask any student about my many pop-culture references, most of which haven’t made sense to young folks for at least a couple decades. I suspect the bottom line is that most teachers have a few of these tropes in our tool-box, little analogies that work for us more than they do for our students.
As my guest speaker moved on to discuss other things, I found my own mind wandering over the range of metaphors we teachers use in our lesson plans, wondering how many really help the students and how many get used for our own benefit.

IAIA
I can think of at least one really great metaphor a friend of mine used to work into a first year seminar to teach the students at The Institute of American Indian Arts. She likened the educational process to flying a plane, and the steps necessary to learn a subject and pass a course to prepping for a flight. What made this metaphor work, mind you, was the part where the students actually got to fly a plane toward the end of the semester. Most metaphors stand or fall in words spoken, dribbled on a page, or splattered on a screen. Her metaphor literally took off, and it did so in the hands of her students.
You can’t get more cool than that!
We tried something similar here at Iḷisaġvik, comparing the educational process to whaling. That may seem odd to some folks, but the Inupiat community of the North Slope does engage in whaling and we are a tribal college, so this fit right in line with promoting the indigenous practices central to our own mission. That said, results were mixed, I think. Whether or not students liked the course, I don’t think that master-metaphor was one of its major selling points. I was never entirely sold on the value of a master-metaphor in a class like that. The one they used at IAIA worked, yes, but I suspect it worked because it was linked to a uniquely personal experience.
It’s hard to compete with flying a plane, yes it is.
I expect the argument-as-warfare meme is all over my logic class. Ah well! For a borderline peacenik, I’m a veritable war-monger when it comes to syllogisms. But this is hardly novel, or even that interesting. Talking about arguments without using violent metaphors? Now that would be interesting. Hey look now, all I am saying is give peace a chance!
…okay someday, maybe I’ll take my own advice on that.
Other metaphors come and go. A topic may yield a race of some sort. An essay can become a veritable construction project. An idea may become rich (in sugar or money, I sometimes wonder). A fact or a sub-theme may become central to a topic. An event may serve as a trigger (World War I anybody?). We can meditate on a topic when we are really just talking about it, and a certain kind of speculation quickly becomes an experiment, or at least a ‘thought experiment’, when we want to endow it with a sense of the sciencey. Half-conscious tropes abound! Most of the time we don’t even think about these things.
Sometimes a student finds their own metaphors, and sometimes they even tell us about them. And sometimes those metaphors turn out to be gold, but I have to admit I’m a tough sell. I often grumble a little inside when I hear these things. Student generated metaphors often strike me as evidence the students have missed the point. I grumble! Perhaps these metaphors would be better thought of as evidence the student has a point of their own. Nah! That approach is just way too wholesome, and we’ll have none of that kinda thinking on this blog dammit!
Coming back to my, …um, …central metaphor in this post, I am wondering if a pedagogical metaphor might be better thought of as your drunk friend who invited you to the party in the first place. He’s the one that’s already three drinks on the road to happy-happy, and if you take the beer he’s offering you, then maybe it’ll be a pleasant evening (and a rich conversation), but you should always find your limit a little before he does. After all, there is a reason this guy is more dialed-in to the party scene than you are. So, it’s less a question of how hard you want to lean on your metaphorical friend than it is a matter of realizing he’s always going to want to do that one more shot that’s gonna totally do you in. Then you just have to say; “No metaphor! No more booze for me. I’m done for now.” …which is of course a metaphor for backing out of metaphorical implications that seem a little silly.
…and on that count alone this last paragraph is a total failure.
What the Hell would I know about parties anyway!?!