Sunday, January 28, 2007

Why posting the solutions isn't the solution

Students always ask me to post the answers to the questions I give them, but I'm reluctant to do so. This makes them unhappy, as they sincerely believe that seeing the right answers is a good way to learn. But I think that seeing the answers often just gives a false sense of confidence.

Say you first try to do the problem without looking at the answer. Because you know the answer is available, you don't spend a lot of time on it. Instead you try do the problem quickly.

If you're able to come reach an answer, you don't spend a lot of time trying to decide whether the answer you've come up with is right, you just check your answer against the posted one. If it agrees with yours, you pat yourself on the back and go on to the next problem. If it doesn't, you look at how your answer differs from the correct one, say "I see how it's done; I won't make that mistake again", and go on to the next problem.

If you can't reach your own answer, you look at the posted one, say "I see how it's done; I'll be able to do it right next time" and go on to the next problem.

Using my "going to university isn't like going to the tanning salon, it's like going to the gym" analogy helps explain why this doesn't really teach you how to solve the problem. Looking at the correct answer is like watching a trainer show you the right way to do squats. You know you need to practice doing them correctly, so you do lots more squats, matching your moves to those the trainer showed you. If you just say "OK, I see" and go on to do bench presses, your squats won't improve.

But you can't go back to the same genetics problem again and learn to do it right, when you already know the answer. Working back from the answer is very much easier than working forward through the forest of possible answers. You need to build the skills that let you evaluate the candidate answers you come up with, testing each one against all the information you have.

It's comforting to think that seeing how a problem is done gives you the skills to do it. But it doesn't. Instead it gives you a false sense of security that can hold you back.

(next time - why going slow teaches you to go fast.)

2 comments:

Tanya Palmer said...

I totally agree!

Liz said...

I can only suggest that some people (me, for example :-}) would continue to make the same mistake again and again without guidance. I learn from doing, as well as from listening and seeing; however, I get frustrated when I can never arrive at the correct solution on my own.

Assuming someone has unlimited time to devote to one single concept in one single subject is a bit unrealistic, as well, I should think.

I hope you'll rethink the practice of not revealing solutions. As you well know, each of the 7 billion of us has unique needs for learning.

All told, though, I find your understanding of the concepts within the study of genetics extensive, and your ability to convey the information in an understandable manner exceptionally good. Thank you!