Jun 15, 2011 8:42 AM

Why Won't You Just Tell Us the Answer?

This discussion comes up all the time in my physics for education majors. I have previously described the course and the curriculum that I use (Physics and Everyday Thinking) – oh, which is awesome.

Let me set the scene. This is near the beginning of the semester. The students have just collected data and built ideas about interactions and energy. In particular, they have looked at changes kinetic energy and changes in thermal energy in situations. The starting question asked the students to create an energy diagram to explain what happens when a baseball player slides and slows down. During this process the player also increases in thermal energy as well as transferring energy to the surroundings (because of a temperature difference).

I don’t recall the exact point of discussion, but it may have been whether the baseball player decreases in chemical energy or not (from using muscles). In the following dialogue (which I am paraphrasing from memory), I will call myself “me” and all the students will be labeled as “student”.

One more note. This discussion is very generic. I essentially have the same discussion every semester at some point.

Student: I think the baseball player decreases in kinetic energy because he is slowing down. Is that right?

Me: Well, do you have evidence to support your answer?

Student: Why can’t you just tell us the answer. You’re the teacher. Your job is to tell us the answer (they didn’t actually say this, but it has been said many times before).

Me: What is important? Is knowing the answer important, or is it important to practice the process of figuring out the answer? Who is the authority? The evidence, or me?

Student: You are the authority. You grade the tests. If we put the wrong answer on the test, then we will get the questions wrong. And how can we know the correct answer if you don’t tell us?

Me: Good point. Let me just say something about the test. If you come to class, participate in the activities, do the homework, I have full confidence that you will have plenty of material to get to a valid answer.

Student: But what if we collect the wrong evidence?

Me: I am pretty sure that everyone here did the experiments correctly. You notice I walk around during class? I am looking at your data. If something crazy happens, I will usually help you repeat the experiment.

Student: I still don’t see why you won’t just tell us the answer.

Me: How many of you have helped someone learn to ride a bike? How do you do that? Do you tell them “oh, look, just push the pedals and don’t fall over”? Or maybe you get on a bike and show them how to ride a bike.

Student: Well, if they are doing something wrong we would tell them it is wrong.

Me: Ok. I think am going to make the claim that the only way to learn to ride a bike is to ride a bike. Is that person going to fall down some? Yes. Do I want them to fall? No. It just is the way it works. Are you going to make mistakes in class? Yes. Will you still learn? Yes. In fact, I think you can’t tell someone how to ride a bike because no one here actually knows.

Student: I can tell someone how to ride a bike. You turn the pedals and you balance on the bike. It is simple?

Me: Is it that simple? It isn’t. Can you just sit on a bike and balance to keep it up? What if it isn’t moving? No one here actually knows how to explain how to ride a bike. Really, it is a very complicated thing. I will tell you the trick. If you are on a moving bike and the bike leans to the left. How do you prevent yourself from falling? You turn left. Search your feelings, you know it to be true.

Pause while students think about the motions riding a bike.

Me: So everyone here can ride a bike, yet know no one could explain this seemingly very important thing. Learning physics is very similar. If you don’t do physics, you won’t learn physics. Do I get scared sometimes when the class is having a discussion and maybe things aren’t going so well? You bet. It is very scary to let go of a class with the possibility that they might make some errors. It is also scary letting go of a child on a bike. You know they are probably going to fall.

I can’t remember how the discussion ended. I do know that they weren’t very happy. But let me make some quick points.

I do tell them the answers. They think I don’t, but many times I do. First, this isn’t a fully inquiry-based course. Really, there aren’t any practical ones. Why? What if you let students collect data and build their ideas own their own? One group might end up calling the energy associated with something moving “momentum”. So, in the PET curriculum the students get definitions of things. Also, just by telling them what experiments to do, I am telling them something.

Most students change their ideas by the end of the course. It takes time, but they do start to think about learning a little differently in the end. Most of them come in with this idea that physics should be all about me giving them “THE TRUTH” and then they give it back to me during the test. After playing with physics for a semester, many see that it is just not this way.

These are good students. There is nothing wrong with them. Then why do they cling to the answer as though it were a raft in stormy waters? Sadly, it is because this is essentially all they have seen. How many of their classes have them build ideas? How many of their classes are something other than things they can put on a flash card? I hate to say this, because we all do things the wrong way. But it could be different.

This is great class to teach (or should I say to be a learning facilitator in). Really it is. I get to interact with the students and watch them struggle and succeed with ideas. You can really see how they change over the semester.