This sounds oxymoronic, but let me explain. Many of your students aced high school by rote learning and regurgitation. As a result, they might not know how to learn actively, and they might not see active learning as beneficial. Don’t blame your students for this: Any tendency they had for active learning was probably squelched by the school system.

Let me relate a relevant horror story. My first semester of teaching, I noticed that most of my students favored passive learning. They wanted me to do nothing but homework. And they didn’t like to solve problems themselves, preferring instead for me to solve them at the board. Furthermore, and most important, they didn’t know that the best way to study physics is to solve lots of problems. So, I told them that to learn physics they’d have to do problems on their own. Then I returned to business as usual. To my great dismay, they bombed the first midterm. I was flabbergasted. After all, I had told them the way to learn physics, and I’d demonstrated good problem-solving techniques in section. What went wrong?

It turns out that despite my speech, many students did not change their study habits. Nor should I have expected them to do so. Why would someone abandon a strategy that has worked all his life, a strategy that got him into a good college, just because some dorky TA says to try something different? Would you change your deeply-ingrained study habits based on one professor’s advice? Here’s my point: Not only must we tell students the necessity of active learning. We must explain why it’s helpful, and show that passive high-school-style learning no longer works.

How can we demonstrate the ineffectiveness of passive learning? Here’s my way: Each week, I give an open-book quiz covering the previous week’s material. The questions are sufficiently hard that rote formula-plugging will not work. Immediately after the quiz, I solve the quiz question at the board, so that students receive immediate feedback. The first few weeks of the semester, many students discover that their old study methods don’t work, and that they will flunk the first midterm unless something changes. Some students who ace the homework assignments by formula-hunting and “copying” discover that they can’t do problems on their own. By the time the first midterm rolls around, many students have started to change their study habits. I help by supplying lots of practice problems.

Almost every TA has, at one point, stormed into the TA office angrily muttering “I showed them how to solve that EXACT problem, and they still blew it on the test. What the fiddlesticks is wrong with them,” or words to that effect. Even the most old and doddering TAs, including myself, continually find ourselves amazed by students’ ability to “forget” something you just taught them. Substantial research has explored this phenomenon, because it’s prevalent among science students of all ages. I usually put little faith in educational research or education theory, but my personal experience 100% confirms the following explanation of why students often don’t seem to retain what you teach, no matter how clearly you present the material.

“Constructivism.” Students do not come to us as “blank slates” ready to be filled with physics knowledge. Instead, they come with thousands of “intuitive preconceptions” about the physical world, based on their everyday experiences. Here’s a common example: Most students think that if an object is moving forward, there must be a force keeping it moving forward. We disciples of Newton’s laws might be tempted to call this a “misconception.” But that’s not quite fair, because if you ask students to justify their belief, they’ll talk about a person walking or a car driving down the street. In those cases, a “push” force is indeed needed to keep the object moving. Students aren’t stupid to generalize from these examples, because friction and air resistance pervade their lives. The crucial question is, What happens when a student holding this intuitive preconception learns Newton’s laws? Our job would be easier if the “classroom physics” simply replaced any contradictory intuitive preconceptions. But this kind of replacement doesn’t always happen. The student does not completely fail to understand Newton’s laws: She can apply them adequately to standard “classroom physics” examples. But the intuitive preconception still inhabits her brain. It has not been displaced by Newton’s laws. And in some cases--both inside and outside the classroom--the intuitive preconception will “click on” instead of Newton’s laws.

For instance, on a Physics 7A test a few years ago, most students said that if an airplane cruises in a circle at constant speed, then the “thrust force” pushing it forward must exceed the drag force. These same students accurately used Newton’s 2nd law to calculate the time needed for a block to slide down a (non-frictionless) inclined plane. Classroom physics beliefs might interact only weakly with intuitive preconceptions, allowing contradictory beliefs to co-exist. Brains don’t have automatic “logic sweepers,” and I dare say that all of us hold some “undiscovered” contradictory beliefs.

Actually, according to “constructivist” educational theory, the cognitive model just presented is a zeroth-order approximation. The intuitive preconceptions do interact with the corresponding classroom physics, at least unconsciously. Drawing upon (sometimes contradictory) beliefs and examples, the student “constructs” an understanding of the relevant phenomena. To zeroth order, this construction might look something like “Newton’s laws apply in these situations, and my preconceptions apply in other situations,” though the student would not present her beliefs in this way, precisely because she has not brought the classroom physics and the intuitive preconceptions into direct logical contact. When the student learns new classroom physics, this information gets integrated into the “construction.” Usually, the updated “construction” matches neither a physicist’s understanding of Newton’s laws nor the student’s preconceptions; it’s a hybrid. Each student constructs her own understanding of the material. Put more roughly, no two students think alike.

The constructivist cognitive model neatly explains why a student can blow a test problem on a topic you just explained in excruciating detail. Your explanation was not “absorbed directly” into the student’s understanding of the world. Instead, it was integrated into, or simply “patched onto,” the student’s previously-constructed understanding of physics. This construction may include intuitive preconceptions (and fuzzy understandings of previously-taught material) that mesh poorly with your teachings. So, it’s not that the student “forgets” what you teach. Rather, your teaching becomes “adulterated” or “overwhelmed” upon integration into the student’s overall understanding. This model also explains why passive learning works so poorly. The more passive the learning, the more weakly the students’ preconceptions interact with classroom physics. The resulting construction closely resembles the zeroth-order approximation of a “divided brain” containing contradictory beliefs.

When a student thinks actively about the new material he’s learning, his intuitive preconceptions and his understanding of previously-taught physics come into play. The student can directly compare the new concepts to his already-constructed understanding of physics. Therefore, the new concepts don’t simply “tack on” to the construction. Instead, the whole construction gets modified to integrate the new concepts smoothly, resulting in a deeper understanding of the new and the old material. To zeroth-order approximation, since the new concepts can directly confront any contradictory preconceptions, the student can modify his beliefs accordingly. This kind of confrontation doesn’t happen in passive learning. Of course, what really goes on inside your student’s brain is more complicated, and not well understood. But it’s safe to say that with active learning, your student’s understanding will be more interconnected, more free of contradiction, and more likely to yield “right” answers. (PDP TA Reference Handbook, 8-23-96)