Professor Tom Cronin: Teaching Physics with Peer Instruction

by Sandhya Rasaili and Diane Dobry

Prior to the 1980s, many physicists and physics educators believed that the basis for determining whether or not a student understood physics was the student’s ability to solve a physics problem.  Much of the physics research during the 1980s also showed that students in physics classes often believed deeply held concepts about mechanics that were contrary to the accepted Newtonian views held by trained physicists.  What was most disturbing was that students, who had been taught the correct or accepted view of physics, continued to hold these preconceived ideas.

The research clearly showed, first, that students were not blank slates and, second, that strongly held preconceptions were difficult to uproot.  Traditional modes of teaching, such as lectures, were also shown to be an ineffective way to change students’ preconceptions to the accepted principles of physics.  Studies, however, did demonstrate that even though a student might be able to solve complex mathematical problems, he or she did not necessarily understand the basic underlying concepts of physics.

As a result, methods of instruction were developed that took the emphasis away from rote problem solving and focused, instead, on conceptual learning.  About a dozen types of interactive learning techniques were developed to answer the question: how do we get students to have a deeper conceptual understanding of critical physics concepts?  One of the techniques developed was peer instruction.

Dr. Thomas Cronin, Physics Professor at SUNY Cobleskill, has applied this method of peer instruction in his general physics classes for more than a decade.   “This is an interactive method of teaching that was introduced by Harvard Professor Eric Mazur in the early 1990s,” Cronin said.  “The main purpose of the peer instruction method is to help students develop deeper conceptual understanding of physical principles by causing and expecting students to think about physics instead of juggling equations.”

The primary focus of the peer instruction method, as with all interactive methods, is to teach students concepts and allow them to be more active participants in their own learning.  In the peer instruction technique, the instructor gives three or four mini lectures in one lecture period with each covering one concept.  At the end of each mini lecture, as a way of testing student understanding, a multiple choice conceptual quiz is given.  First, each student thinks independently about the conceptual question and chooses a response.  Once they have thought about the question on their own, they then discuss it with their peers.  After deliberating about the question for a minute or two, they respond by holding up a card indicating their choice of the correct answer (A,B,C,D, or E) according to the options presented.

By doing this, the instructor can evaluate the students immediately and know how many of them understand the concept.  If most students demonstrate such understanding by providing the correct response to the conceptual quiz, the instructor moves on to the next mini-lecture.  If the instructor finds that not enough students understand the concept, the material is presented a second time in a different way.  Clearly, one of the goals of this method is to bring the whole class along at the same rate and to be sure everyone understands the concepts before starting a new topic.

In order for peer instruction to work, several things have to happen.  Students are given a daily reading assignment, which prepares them for engaging in the mini-lectures. A quiz given by the professor at the beginning of each class provides additional motivation for students to read the assignment.

[quote from Prof Cronin about the importance of students preparing for class by doing the daily reading OR about the quizzes]

Another critical part of what makes peer instruction work is pre- and post-testing.   A pre-test on the first day of class allows the instructor to evaluate the student’s basic understanding of Newton’s law of motion.  A post-test, administered after mechanics has been covered evaluates students’ mastery of Newtonian concepts.

“Pre- and post-tests give the professor a way of measuring both student progress and the success of the instruction in helping students to achieve the goal of the course,” Cronin said.

Professor Cronin has been using peer instruction in his physics classes  at SUNY Cobleskill as well as in 2008-2009 when he received a Fulbright scholarship to teach at Ataturk University in Turkey. He introduced peer instruction techniques there to teach students of electrical engineering and computer science education.   One of his Turkish colleagues also adopted it as a method of instruction.

Although he says he has succeeded in improving his SUNY students’ conceptual understanding of physics, his record has not equaled that of Eric Mazur.  “In part, this may be because of the broad range of abilities, interest, and preparation of the students taking the class,” Cronin said.  “Nearly half of the students who take physics have not had any high school physics classes, which usually presents a significant disadvantage for those students.”

In Turkey, he found that peer instruction was not as effective as he has found it to be in the US, for a number of reasons.   He found students there to be very resistant to this new teaching and learning method.  He also noticed that although many students in his classes in Turkey had three years of high school physics, their conceptual understanding was equal to that of an individual who had only taken one year of high school physics.  He believes this was the result of students learning to solve problems without conceptual knowledge in order to prepare for a national exam.

“This showed me the validity of the idea that learners can solve problems without actually understanding the physical concept,” he said.