Clickers and Peer Instruction in Physics 101:

Enhancing engagement, interaction and (hopefully) understanding

Neepa T. Maitra

Hunter College and the Graduate Center of the City University of New York

Physics has a notorious reputation…• People often tend to remember their physics courses with dread. They may come away thinking physics is tedious, or abstract, confusing, hard, and/or not really relevant.

• Demonstrations – may be fun but often don’t help, especially when equipment is involved and complicates the basic physics use the simplest every-day examples possible to avoid students fixating

on irrelevant aspects

• A lecture where the professor professes for an hour or more usually doesn’t hold the attention of the students.

• It’s not about memorizing, instead it is about understanding.

• Actively involve students in their own learning during lecture, with focus on the concepts Peer Instruction Method of Eric Mazur

Peer Instruction

• Method developed by Eric Mazur at Harvard University

• Lectures interspersed with multiple-choice conceptual questions, called ConcepTests, designed to expose common difficulties in understanding the material.

• Students are given 1-2 minutes to think about the question and enter answers individually through clickers. Bar graph comes up showing class distribution of the answers.

• Students then spend 2-3 minutes discussing their answers in groups of three to four, and told to “convince-your-neighbor of your answer”. Another bar graph is then taken of the class’s revised answers.

• Professor then discusses the question and answer, and can adjust the subsequent material depending on the results of the bar graph.

Peer Instruction

• The “convince-your-neighbor” process forces the students to think through the arguments being developed, and enables them (as well as the instructor) to assess their understanding of the concepts during the lecture.

• Students make significant gains in conceptual understanding as well as gaining problem solving skills comparable to those acquired in traditionally taught classes – not just at Harvard, but elsewhere too.

• Can implement in almost any subject and class – so I tried it in Physics 101 at Hunter!

• Instant feedback both for students and for professor

Physics 101 at Hunter

• “Basic Concepts of Physics” – a one semester terminal course

• We cover a huge range of introductory physics – topics that usually cover two semesters in the other introductory physics courses -- but with emphasis on concepts, not on equations

• Enrollment usually ~ 70-80

• Mixture of majors – from nursing to architecture to film to philosophy…

• Students enter with hugely varying background and abilities

• Next slides: some examples of the “clicker questions” and their responses…

An Example:

Clicker Question

When the pellet fired into the spiral tube emerges, which path will it follow? (Neglect gravity).

This is how the class answered:

Answer B:

While in the tube, the pellet is forced to curve, but when it gets outside, no force is exerted on the pellet and (law of inertia) it follows a straight-line path – hence, B.

Before: After:

Some of the B’s convinced some of the A’s and C’s that B was right – and indeed it was!

Another ExampleClicker Question

Which has more photons, a beam of red light or a beam of blue light of the same total energy?

A) Red

B) Blue

C) Both same

D) Cannot be determined without more information

Answer: A, red.

Since red light carries less energy per photon and both beams have the same total energy, there must be more photons in the beam of red light. (c.f. Two equally heavy bags of ping-pong balls and bowling balls – there must be more ping-pong balls)

The discussion amongst peers worked…

Before: After:

…but not as well as one might like -- so we spend some time discussing the answer, calling on people who chose each of A,B,C,D to explain why they did…

Before, no consensus, but slight majority for C.

After discussion, trend to convergence, and A wins!

An Example for you to try?Clicker Question

1. The preserver upstream.2. The preserver downstream3. Both require the same.

Suppose you and a pair of life preservers are floating down a swift river, as shown. You wish to get to either of the life preservers for safety. One is 3 meters downstream from you and the other is 3 meters upstream from you. Which can you swim to in the shortest time?

Suppose you and a pair of life preservers are floating down a swift river, as shown. You wish to get to either of the life preservers for safety. One is 3 meters downstream from you and the other is 3 meters upstream from you. Which can you swim to in the shortest time?

1. The preserver upstream.2. The preserver downstream3. Both require the same.

Answer: 3, same time.

You, and both life preservers are moving with the current – relative to you before you start swimming, neither of the life preservers are moving.

An analogy: We can think of things on earth as being in a “current” traveling at 107 000 km/h relative to sun.

And the results from the class:

Ooops!! So it didn’t quite work here – but the class then really really wanted to know the right answer!

And we then go over it, and the related physics concepts, in more depth.

Before: After:

Another Example Clicker Question

In the photo-electric effect, is it brightness or frequency that determines the kinetic energy of the ejected electrons? How about the number of ejected electrons?

A) Brightness determines both KE and number

B) Brightness determines KE and frequency determines number

C) Frequency determines both KE and number

D) Frequency determines KE and brightness determines number

Answer: DThe electron’s kinetic energy depends on the frequency of the illuminating light. With high enough frequency, the # of electrons ejected is determined by the number of photons incident, ie. on the brightness.

And it worked again here too :

Before: After:

A Trickier Clicker Question

Tracks A and B are made from pieces of channel iron of the same length. They are bent identically except for a small dip near the middle of Track B. When the balls are simultaneously released on both tracks as indicated, the ball that races to the end of the track first is on

1. Track A.2. Track B. 3. Both reach the end at the same time.

And this is what the class thought:

Before: After:

Hmmm, so what is the right answer ??!!

Tracks A and B are made from pieces of channel iron of the same length. They are bent identically except for a small dip near the middle of Track B. When the balls are simultaneously released on both tracks as indicated, the ball that races to the end of the track first is on

1. Track A.2. Track B.3. Both reach the end at the same time.

The ball to win the race is the ball having the greatest average speed. Along each track both balls have identical speeds—except at the dip in Track B. Instantaneous speeds everywhere in the dip are greater than the flat part of the track. Greater speed in the dip means greater overall average speed and shorter time for a ball on Track B.

Note that both balls finish at the same speed, but not in the same time. Although the speed gained when going down the dip is the same as the speed lost coming out of the dip, average speed while in the dip is greater than along the flat part of the track.If this seems tricky, it’s the classic confusion between speed and time.

Answer: 2

It’s actually B !!

(I tell them this is a sort of challenge question, not something that would be on the test…)

My experience with Clickers and PI in 101

• Certainly keeps the class as a whole more engaged and awake!

• Several tell me they really value the chance to try to explain and say it helps them understand and reinforce what they’ve just learnt.

• Students feel confident when able to explain to others their reasoning.

• Students share confusions with each other and help sort them out

• Even when the answer doesn’t converge to the right answer, the students then really really want to know the right answer !!

(And it can be funny and fun !)

• To make more effective: I need to construct some questions more carefully

• Most of the more able students seem to enjoy and benefit from it.

• Some of the less able students enjoy it but it is not clear if they benefit.

• Are the test scores better? I haven’t done any controlled studies of this myself…but see next slide…

On-going Research on Peer Instruction• Carefully controlled studies at Harvard have shown PI significantly

increases students’ conceptual understanding.

• For the more quantitative intro physics classes, PI-taught students have at least as good problem-solving abilities than traditionally taught students.

• Also found to decrease student attrition.

• Devised at Harvard – how well does it work at institutions which are not much like Harvard? (i.e. most places!)

-- Carefully controlled studies at a 2-year community college in Canada (John Abbott College) found it still works as above.

-- Students with less background knowledge gain more from PI than traditional lecture at the community college. Not found to be true at Harvard.

-- More and more places are using it.

Some references:

(1) Peer Instruction: A User’s Manual, by Eric Mazur, Series in Educational Innovation (Prentice Hall, Upper Saddle River, NJ, 1997)

(2) Peer Instruction: From Harvard to Community Colleges, by Nathaniel Lasry, Eric Mazur, and Jessica Watkins, Am. J. Phys., 76, 1066-1069 (2008).

(3) Peer Instruction: Ten Years of Experience and Results, by Catherine Crouch and Eric Mazur, Am. J. Phys., 69, 970-977 (2001).

(4) http://mazur-www.harvard.edu

Thanks for listening!

Another way to enhance student participation:

Prediction of Simple Demos

Example: Air resistance with a piece of paper and a book….