The Importance of Distraction

Kate recently signed up for Facebook, and I was talking to her earlier about some of the options for wasting tons of time entertaining yourself with Facebook, and mentioned the ever-popular trivia quizzes and “personality tests” and the like. Of course, I had to caution her that most of the quizzes are really lame, because the people making them up don’t know how to make a good quiz.

Making up good questions is a skill that takes time to master. The key elements that the people behind most Facebook quizzes are missing are good distractors– the plausible-sounding wrong answers that lead people astray. If you want to make a test that actually tests people’s knowledge, rather than their ability to parse the question carefully.

For a silly example, here’s a music trivia question:

That’s written to have reasonably good distractors. You’ve got four similar-sounding names and one wild card. Even a person who knows the correct answer will have to stop and think a bit. Someone who only knows a tiny bit about music is likely to jump for the obvious wrong answer, and someone who knows just enough to know that the name isn’t obvious will more or less have to guess.

What you tend to get on Facebook trivia quizzess is more like:

This is practically an insult to the quiz-taker. Two of the answers are solo artists, not bands, and two of the bands on the list weren’t recording hits in 1988. You don’t have to know much of anything about pop music to get the correct answer– you can easily eliminate all the wrong answers as being transparently dumb.

The same thing carries over to writing physics questions. For example, in an introductory mechanics class, I might very well use a question like this:

A car with mass m is moving along a test track with speed v. The driver slams on the brakes, and the car comes to a stop in a distance L. The driver re-starts the car, increases the speed to 2v, and repeats the test.

(This is still kind of an easy question, but I don’t want to give away any of my really good material on the blog.)

The key thing here is that the wrong answers provided with the question are the sort of thing that students arrive at through common misconceptions. When they get the question wrong, you learn not only that they don’t know the right answer, but you also learn something about how they got it wrong. You get information about the train of thought that led them to the wrong answer, which is critical information if you’re trying to teach the key concepts of classical physics.

And, as a bonus, the correct choice of wrong answers makes it difficult for students to bluff their way through a quiz or test with only a tiny bit of knowledge. And that’s something that trivia-quiz writers could stand to learn from.

(The correct answers to all of the questions in this post are trivially Google-able, but that would be cheating…)