Making Mistakes and Learning

picture of Harry KellerBy Harry Keller
Editor, Science Education

You’ve probably heard that you learn by making mistakes. The bigger the consequences of your mistake, the more likely you won’t forget.

I used to live in Massachusetts where I built a house with a 400-foot driveway. Where I lived, about 35 miles west of Boston, there was plenty of snow in the winter. At first, I just shoveled the driveway. I was young, foolish, and into doing it yourself. After a particularly snowy year, I gave in and purchased a nice big snowblower.

If you’ve ever used one of these, you know that springtime provides the real challenge. The snow is wet and tends to stick in the chute. You have to dig it out fairly frequently. Just below the chute is the high-speed impeller, a very dangerous bit of the equipment. Snowblowers have a safety device that prevents you from sticking your hand into the chute, but my arms are long enough to defeat that device. I can put my hand into the chute without stopping the impeller and did so many times before the fateful day on which I put my hand in too far.

I had on thick leather mittens, but they didn’t help a bit. Although they were not damaged in the slightest, my middle finger’s last segment was decimated, essentially destroyed. The pain was extreme. My wife drove me to our nearest emergency clinic, about a half-hour away. All the while the pain was escalating. I nearly fainted on the way in and did collapse for a moment on the floor of the elevator. 

The people there were very nice about everything once I was checked in and had passed triage. First, they gave me a large injection in my butt for the pain, but it did nothing. That’s how much it hurt. They had to stop the pain before they could wash and sterilize the shattered remnants of the end of my finger. So, they performed a “ring block” whereby they inject anesthetic into the webbing between my fingers. Although this is a very painful injection, I barely felt it. Then, the pain subsided.

After cleaning the mess that was now the end of my finger, they took a good look at it and determined that the bone was totally shattered. My finger tip was being held together by only my fingernail. They sent me to a specialist another half hour away. My first visit was to a facility in the suburbs. The specialist was in the city. He did a great job of salvaging my finger while regaling me with horror stories of patients he had seen. It would be years before I recovered most of the feeling in that finger tip.

I learned my lesson very well. Never again did I use the snowblower without carrying a stick to clean out the chute. My fingers would never enter that evil space again.

This sort of story illustrates the power of making mistakes in the process of learning. In education, it’s important to let students make errors and to have them know as quickly as possible that they have erred. Trial and error can be a great learning tool. Yet, it can be misused.

Consider what it is that you wish your students to learn before subjecting them to this “trial by fire.” For most instances, for example learning mathematics by doing homework assignments, you’re dealing with modest rewards and punishments while having a clear outcome in mind. However, this may not be the case with the typical science labs being used throughout middle school, high school, and college. Science teachers often say that they would like their students to have the opportunity to make mistakes. Sounds like a good idea, doesn’t it?

Consider the alternative, too often seen in today’s classes. I have visited a large number of science classes, and my colleagues continue to do so. I recall one that I visited where they were about to use my online hands-on science labs, and the teacher took some time before starting to explain the lab and the results expected. I was appalled but remained quiet because I did not wish to create problems with this teacher. Our labs have been carefully designed so that the results are not known beforehand, and students can figure things out for themselves. After the class, I asked the teacher why he explained so much before the lab. He answered that he did not want to see his students fail.

There’s nothing wrong with making wrong guesses or not understanding the data immediately. That’s how you learn. Yet, many of our classes, at all levels, have teachers who smooth the path so much that no one truly learns any of the more valuable lessons available in schools. It’s important to be on your own and use your own ideas, whether they turn out correctly or not.

Note that the teacher mentioned above made a mistake. Was that good? No, because he did not suffer any measured consequences. How can you learn from a mistake that you don’t know you made? There were consequences, of course. However, his students were the ones who suffered, not him.

I mentioned that this valuable concept of allowing students to make mistakes can be misused. In my field of science, here’s how that can happen in science labs. In 2004, the National Research Council (NRC) published America’s Lab Report. In it, they opined that the typical high school science lab experience is “poor.” They then went on to describe the reasons that these experiences are poor. Among these are weak or no connection to course material and lack of relevant goals for the lab experience.

In a school (educational) science lab, students have three separate experiences combined with various questions and reports they must answer and write, respectively. These experiences are:  setting up, data taking, and data analysis. The setting up part is also known as the lab procedure.

Many of the science teachers who promote the efficacy of making mistakes are referring to the procedure part of the lab experience. Drop that test tube, and you learn not to do so again. Yet, that’s not the science part of the lab at all. A student who is incapable of picking up a test tube due to some injury or affliction that limits fine motor skills still can do good science. The extreme case most know about is Stephen Hawking. Many scientists have limitations that prevent them from being great laboratory technicians but have great careers in science.

The most crucial part of the science laboratory experience must be the third part where you analyze the data by looking at it, displaying it in various graphical forms, attempt to fit it to models, and finally make conclusions and write a report explaining all of this work you did. This process involves wrestling with ideas and how well they fit with what you’ve found out. Here is the place where making mistakes makes a difference. Try graphing the data this way or that. Try some arithmetical manipulations to make more sense of the data. Perform error estimates. And so it goes. Some will work; some will not. You will learn about empirical data and about the particular science that your experiments were probing.

Nevertheless, you will not have the same experience if someone just hands you the data to analyze, which is why so many consider the science lab to represent the soul of a science course. Unless you take those data yourself, they are a bunch of abstract numbers to most. Yes, professional scientists may well work with data from other people, but students don’t have the sophistication to profit well from such an activity. They should understand where those data came from and will have a much greater understanding if they acquire those data point by point themselves.

You could argue that the first part, the procedure, is just as important, but I will suggest that you can have a good feeling for that part from other experiences, including an excellent video. Of course, it’s best of all when you do all three yourself, but it’s also expensive and time-consuming. This first part, the procedure part, is where too many science teachers focus their desire for students to make mistakes.

What is the result of students making procedural mistakes? On the positive side, they may learn to improve their lab technique and be better lab technicians. However, few will ever be in a position, after graduation, to exercise this skill. On the negative side, they may have lost an hour’s worth of effort by a single slip. Usually, this time is not refundable; they cannot do the experiment over and won’t have their own data to work with. They have learned the unpleasantness of working in a science lab. Either they have no data, insufficient data, or externally provided data. So, they find themselves in an unsatisfactory learning situation.

If the lab was one of the ones labeled by the NRC as poor, little has been lost because nothing would have been gained anyway. For genuinely decent labs, the loss harms the learning.

The next time a science instructor tells you that he or she would like to see their students making mistakes in the lab, check on what sort of mistakes are being promoted as good. Procedural mistakes ruin the experience. As much of the procedure as possible should be taken out of students’ hands and shown in some way, demonstration or video. Do not allow that instructor to get away with promoting a pedagogically inferior idea. Making mistakes only benefits the mistake maker when the outcome fits a learning goal. Breaking glass in a lab has no benefits for learning science.

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