How I Use a Card Trick to Teach About Science

Every year when I start a new class, I always take some time on the first day to discuss science & the scientific method. But I have my own fun & unorthodox spin on it: I first tell the “Dragon in My Garage” story, and then I go on to describe the scientific method in a very fun manner.  In short, I do a card trick…

The way I start is to ask my students if they’ve ever been to a family reunion or other gathering where someone present is doing card or magic tricks (suppose this person is “Old Uncle Harry”).  And say Uncle Harry does a particularly impressive card trick (some kind of “mind reading” or mentalism trick); what is likely to be the first response from the children present?  If you said “Do it again!” that’s a pretty good guess, but second to that I’d say the next most common response is “How did you do that?”

“How did you do that?” – contained within this question is a lot of information, folks.  First, it shows that even little kids can think critically & skeptically, because if Uncle Harry responds “It’s magic, kid (wink, wink)” even children know something’s fishy.  Second, it shows that kids want to know some kind of plausible, naturalistic solution to the supposedly “magical” phenomenon they just witnessed.

Then I play off this curiosity & natural skepticism: I ask my students what a particularly curious kid might do to figure out Uncle Harry’s trick (because really good magicians don’t reveal their tricks too easily).  Invariably, they respond that perhaps the first step would be to do some research on card tricks by looking up info on the Internet or going to the public library.  Then, once they think they’ve got an idea of the process, what’s the next step?  “Experimentation” comes the reply – in other words, the student might try to replicate just how the trick is performed by getting their own deck of cards and trying to repeat the phenomenon they observed earlier.  Depending upon their relative success or failure at replicating the trick, they may have to go through this process multiple times before coming to a meaningful conclusion as to how the trick is done.

And that, as I tell my students, is the scientific method in action.  Scientists are going through the very same investigative process as are those kids attempting to figure out Uncle Harry’s magic card trick.  They are attempting to figure out the “tricks” that nature is playing upon us all the time, and to do so they must study, research, hypothesize, and experiment in order to form a coherent & naturalistic explanation for the phenomena we observe (sorry, no “magic” allowed 😉 )

And then I ask the question I’ve been waiting to ask for the entire class: “So, having said all of that, do you want to see a trick?”  The answer is always yes, and it’s always a satisfying and enjoyable trick.  This very trick I performed at the “Skepticism in the Classroom” workshop at The Amazing Meeting 8 for about 150-200 people, most of whom were teachers, and it was a real hit.  In fact, it was such a hit that I decided to write up the solution for it, and I share it with you here… enjoy… 🙂

The Importance of Being Wrong

I was initially planning on titling this post “The Importance of Being Right” – but then I thought that we all pretty much already knew that. We all know that if you don’t do the engineering calculations correctly, for instance, the car engine doesn’t work. Or if you don’t really know what you’re doing with biochemistry, the drug/vaccine/antibiotic you’re making doesn’t cure disease effectively. Clearly, because the universe functions according to a set group of natural laws we must make sure that our science & technology fits with those laws. To insist the universe adhere to our own preconceptions while ignoring how it really behaves is a sure path to self-delusion. Taken to its logical extreme, such thinking leads towards solipsism – also known as the philosophical idea that “My mind is the only thing that I know exists.”

Aside: I like to ask those espousing solipsism whether or not they look both ways before crossing the street – strangely enough, the answer has always been “yes.” The following cartoon also illustrates the silliness of taking solipsism too seriously…

So, we all know that because there is an external reality beyond our own mind that functions independently of that mind, the importance of being right is unquestionable.

But what about the importance of being wrong? I will tell you this… it is very important to not only be wrong (to a certain degree) but, more importantly, how to learn about why we were wrong. I had the idea for this post because I was at my martial arts dojo today, and I was trying to help a less-experienced student with a technique which is a defense against mae-giri, also known as a front kicking attack. As I attacked him, he had a hard time avoiding my kicks, and he grew frustrated that he wasn’t able to perform the technique easily. I responded by telling him not to let it bother him, because he’ll do it wrong 100 times before he gets it right once. Hopefully, throughout the process of doing it wrong so many times, my junior student will learn how to do it correctly. We learn by making mistakes.

It is no different in my classroom – I’ve dealt with many a frustrated student who was having trouble learning how to do a physics problem or attempting to work their way through a lab. Only with constant practice, and by making a plethora of errors, can most students effectively learn what not to do. As I tell my students, the reason why I’m so good at physics is because I’ve had so many experiences making mistakes! 🙂

There is another issue – many students are stuck on always getting the “right” answer in science class, and sometimes teachers (myself included) are guilty of overly reinforcing this attitude. But to get the process – and not merely the facts – of science across to our students properly, I think we have to walk a fine line as educators. And this is where the importance of experimental lab work in science classes cannot be overstated.

In my classes I require my students to do a lot of lab work. Many times I purposefully set up scenarios in which the students are to draw conclusions from their data. A perfect example is when I ask them to make a series of measurements on the period of a simple pendulum, and they are to isolate three variables in the process – mass of the pendulum bob, amplitude of the swing, and the pendulum’s length. I then ask them to, based upon their data, determine how (or even if) each of these variables affects the period of the pendulum as it swings to and fro.

The responses I get from my students are interesting, because despite the fact that they’ve collected the data, many answer the question incorrectly. Many will say that the more massive the pendulum bob or the smaller the amplitude, the shorter the period of the pendulum. And this is incorrect – under controlled conditions, the period of a simple pendulum is only affected by its length! That is, the longer the pendulum, the longer its period, and the mass & amplitude don’t affect the period.

Often, when I point this out to students, they don’t believe me at first. But then I point to the data which they collected, and then they see it – they allowed their preconceived biases of how they thought the pendulum should behave to creep into the scientific process. In so doing, they were giving me what they thought ahead of time to be the “right” answer, instead of gleaning out the proper answer from their data in a non-biased manner. Their conclusions were wrong, but when it comes to such a lesson I want them to understand why they were wrong – experimenter bias.

I mention all of this because it should be noted that science cannot be done in a vacuum – this is why we often speak of a scientific community. Scientists are just as human as anyone, and we all come to the process with our own biases & preconceptions, and – just like my students – we sometimes see what we want to see. But the scientific endeavor is different from all others in one critical way – peer-review. Peer-review is necessary in science precisely to make sure that our biases, preconceptions, mistakes, and sometimes outright fraud do not unduly influence the results of our explorations. Through peer-review we often catch each others mistakes, we demand that proposed hypotheses be falsifiable, we insist that experiments be repeatable and verifiable. As such, we get things wrong all the time in science, but we figure out why we get it wrong – and this puts us closer to the path of getting things right. Through this rigorous peer-review process, we see that science is self-correcting.

And that is a major distinction between science and pseudoscience. The scientific community does peer-review, learns from its collective mistakes, and employs a largely self-correcting process in its search for our understanding of the universe. Pseudoscientists of all stripes – astrologers, homeopaths, creationists, and conspiracy theorists to name a few – make this one fatal flaw: lacking adequate peer-review, they don’t learn from being wrong. Rather, they insist upon molding the universe to fit with their worldview, and in so doing they delude themselves & others. This cartoon illustrates the point rather well…

Now I’m off to grade some exams. Hopefully my students have learned from earlier mistakes.