One-Best-Answer Questions

You may have noticed I haven’t been blogging as frequently this summer.  That due, in part, to the fact that I’m teaching a summer school course on the history and mathematics of cryptography.  Monday night I broke out a set of clickers for use in the three-hour class session.  Since the course is not just a math course, but a history course, as well, this gave me the chance to try my hand at writing and using clicker questions that didn’t have single correct answers.  Most were what are often called “one-best-answer” questions, questions where the students must select the one response they feel best answers the questions from several responses that have merit.  Here’s an example:

Which of the following was the most significant factor in the Allies’ cryptography victory over Germany?

1. The Germans’ codebreaking efforts were not centralized like the Allies’.
2. The Germans were the attackers, not the defenders.
3. The Germans excluded groups of people from their cipher bureaus.
4. The Germans had difficulty facing the possibility that their ciphers could be broken.

When my students responded to this question, there was a clear majority for reason #4.  It’s likely the students were influenced by our textbook, the author of which makes a good case for reason #4 but doesn’t discuss reasons #1, 2, or 3 in as much depth.

I think it’s important to consider how to handle a situation like this where the textbook author leans in a particular direction.  Had I asked this as a ranking question, in which students were asked to rank the four reasons in order of importance, choice #4 would still have been the clear winner, but the relative positions of choices #1, 2, and 3 would have been worth discussing.  Re-voting after that discussion might have yielded less support for choice #4, helping students see some of the complexities of the question not addressed in the textbook.  I’ll give that a try next time around.

Here’s another example:

Why might the Americans and French conclude that the Enigma cipher was unbreakable prior to the start of World War Two?  (Select the strongest reason.)

1. They were intimidated by the fact that it was produced by a machine.
2. They lacked information that could only be obtained by espionage.
3. Not at war, they weren’t motivated to persevere.
4. They didn’t take the multi-disciplinary approach the British did.
5. They didn’t have a couple hundred years to spare as with the Vigenere cipher.

As with the previous question, the textbook author argues persuasively for a particular choice (#3 in this case), which affected the results.  Choice #3 was indeed most popular, but a few students indicated that the lack of motivation mentioned in choice #3 might have led to the issues described in the other choices.

It’s worth noting that the answer choices above were adapted from student responses to a pre-class reading question (one using the same question prompt, but open-ended).  When I pointed this out to the students, it seemed that the students were perhaps a little engaged because their peers’ opinions were expressly used in the construction of the question.

How have you used one-best-answer questions?  Have you encountered the problem of the textbook influencing students perhaps more than it should?