The students are scattered around the room in their study groups going over a problem set that they had last night for homework. Jasmine comes up to me with a perplexed look on her face. “I’ve tried three times and I just can’t see how you got this answer for number five.” She holds up the answer key and her journal to compare the two.

“Well, Jasmine, that’s because your answer is right, and the one I put down on the answer key is wrong. See, I substituted the wrong number for the initial velocity here.” I point to it.

“Aha, she says, “so that’s it! What a relief!”

“Didn’t anyone else in your study group have the same problem?”, I ask.

“Yeah, but they just copied down your version in their journal corrections and moved on to the next question,” she says.

That brings me up short. It’s clearly time for a little talk with the class. I wait until it looks like everyone is done with that problem.

“Okay, I’m sorry to interrupt, but I’d like to check something out,” I say. “How many of you have a different answer for number five than the one on the answer key?” No hands go up.

“So here’s the problem — those of you who copied down my answer are confused about why you have answer keys to work with. You are still thinking that getting the correct answer is the purpose. It is most definitely *not. *Your job is actually to discover whether you are able to do the problems correctly on your own, and if you aren’t, to isolate the difficulty you are having and work on mastering that.

“In other worlds, when you see a discrepancy between your work and mine, the most important thing you can do is to figure out exactly why that difference exists, whether you made a mistake or I did. That’s where you do the real learning. Copying over the right answer without understanding why it is right and your answer was wrong is a complete waste of your time — you are missing the chance to learn from your mistakes.

“So now I want you to go back to that problem and see if you can discover what mistake I made and what the correct solution should be. I’ll check back with you in a few minutes to see if everyone was able to figure it out. And from now on, I’m going to intentionally make a mistake in my answer keys every once in a while to help you see if you’re really using it well.”