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February 2001, Vol. 4 No. 1 Print Ready ArticlePrint-Ready
Demonstrations and Active Learning During Lectures
Associate Professor Andrew T.S. Wee
Department of Physics

Should lectures merely transmit information that is already printed in the textbook? Do our students actually learn during class time, or do they simply feverishly scribble down everything we say, hoping somehow to understand the material later? Can large lectures be thought-provoking, or only sleep-inducing?

Although there is considerable evidence that traditional approaches are often ineffective, most undergraduates in universities worldwide continue to be taught in lectures, often in large classes with more than 100 students. Alternative approaches such as Workshop Physics (Laws, 1991) that eliminate formal lectures have been used successfully, but substantial structural changes in the curricula are required for large universities such as NUS to implement such programmes. I shall describe my attempts to help enhance student learning of physics within the existing lecture/tutorial structure at NUS based on my experiences in teaching an introductory physics module to a large class 1 . Many of these ideas may also be useful in the teaching of other laboratory-based courses.

Lecture Demonstrations

There is often no better way to engage a large undergraduate class at the start of an early morning 2-hour lecture than with a well-chosen lecture demonstration. For example, I have demonstrated how to pull a ten dollar note from under an inverted bottle without toppling it (Newtonian mechanics), scooped freezing liquid nitrogen at -196 °C from a dewar with my bare hands (Thermodynamics), and played yo-yo (rotational dynamics) in class. Of course the particular demonstration is chosen to highlight a physics concept that would be expounded in the lecture, and students are invited to provide a physical explanation. This normally results in a discernable increase in the attentiveness of the audience, especially since my lectures often start at 9 am, a time when most of the audience is brain-dead!

My suggested plan for an interesting lecture demonstration involves these steps:

  1. choose a simple but effective demonstration that students can relate to in their daily lives;

  2. begin by posing a question or asking for a prediction of the outcome;

  3. get a student volunteer to help;

  4. do the demonstration;

  5. ask again for explanations;

  6. provide a general explanation on why it works (or does not); and

  7. invite students to submit a more detailed explanation.

Do not take longer than 10 minutes for the whole event in order to sustain interest, and flow quickly into the main body of your lecture. Regarding point (3), insurance might be useful since a student was hit by a water rocket in my class! For a 2-hour lecture, posing a question using a demonstration before the half-time break encourages discussion and self-experimentation to continue.

Active Learning

While engaging the audience is important, we must create an active learning environment throughout the lecture class. How can this be done in a large class? Sokoloff and Thornton (1997) have developed a teaching and learning strategy called Tools for Scientific Thinking Microcomputer-Based Interactive Lecture Demonstrations (ILDs). They used real-time data made possible by microcomputer-based laboratory (MBL) tools to engage the students during a lecture, and convert the usually passive lecture environment to a more active one. Briefly, the steps of their procedure are:

  1. describing the demonstration without MBL tools;

  2. getting students to record their individual predictions in a Prediction Sheet;

  3. letting students engage in small group discussions;

  4. getting students to record their final predictions as a result of their discussions;

  5. eliciting common student predictions from the class;

  6. performing the MBL measurement, suitably displayed;

  7. students filling out the Results Sheet; and

  8. instructor discussing analogous physical situations based on the same physics concept. The authors reported that student understanding of physics concepts are significantly improved when such ILDs are used in lectures.

The Use of IT and the Web

While there are several commercial MBL and other teaching software packages available, the lecturer must be comfortable using them in his/her lecture. It would be ideal for each lecturer to develop his/her own software package, but this takes substantial resources and time. I chose not to use such commercial packages, but have preferred to be selective about my resources to suit my individual style. Nevertheless, the principles of active learning described previously can still be applied. The Internet is a rich and free source of computer-based lecture demonstrations that can be selectively used in the lecture. All that is required is a computer (and projector) with an Internet connection in the lecture theatre; this is readily available in many NUS lecture theatres. An example of a good Internet source that I have used to illustrate physics concepts is The Virtual Laboratory 2 which contains numerous links to Java Applets for visualization and demonstration in physics. Such tools are particularly useful when it is not physically possible to do a real demonstration, for example in demonstrating the kinetic theory of gases 3 or when showing the motion of charge carriers in a transistor 4.

On the use of IT in general, I wish to reiterate the fact that IT is just a tool and the web is just another medium of information communication. Even the most sophisticated use of IT will not a good lecture make. Delivering a good lecture is as much an art as a science, and enthusiasm and commitment are key ingredients for its success.

The Use of Questions

In order to address misconceptions about learning, Eric Mazur (1997) developed the method of Peer Instruction, which involves students in their own learning during lecture and focuses their attention on underlying concepts. Lectures are interspersed with conceptual questions, called ConcepTests, designed to expose common difficulties in understanding the material. The students are given one to two minutes to think about the question and formulate their own answers. They then spend two to three minutes discussing their answers in groups of three to four, attempting to reach consensus on the correct answer. This 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 even before they leave the classroom. Meltzer and Manivannan (1996) made use of flashcards (labelled A to F) to elicit immediate student responses to questions posed during the lecture (with multiple-choice answers). These questions usually precipitate lively class discussion regarding the different choices.

When I pose questions to a large class, I often get good voluntary responses. I have also asked students to discuss concepts in small groups during the lecture, which turns the usually quiet environment into a “fishmarket”—a desired outcome! Naturally this activity has to be selectively used or the lecturer may not be able to cover much ground in class.

Concluding Remarks

I have briefly described how the use of demonstrations, IT and questions can promote active learning during lectures. The ultimate objective must be to facilitate student learning. If this focus is lost, then the use of even the most sophisticated techniques can distract rather than help the learner. A good lecture has to be well-orchestrated and rehearsed, incorporating the most suitable means to facilitate learning. It involves much effort and character building, but is nevertheless rewarding.


Laws, P.W. ‘Calculus-Based Physics Without Lectures’. Physics Today. 44(12). 24–31. 1991.

Mazur, E. Peer Instruction: A User’s Manual. New Jersey: Prentice Hall, 1997.

Meltzer, D.E. and Manivannan, K. ‘Promoting Interactivity in Lecture Classes’. Physics Today. 34. 72–76. 1996.

Sokoloff, D.R. and Thornton, R.K. ‘Using Interactive Lecture Demonstrations to Create an Active Learning Environment’. The Physics Teacher. 35. 340–347. 1997.


1 PC1131 Physics I, web page URL:

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2 The Virtual Laboratory, web page URL:
Links to other resources can be found at

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3 This Java applet simulates a 2-dimensional gas of hard sphere:

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4 A good site for the visualisation of semiconductor physic processes is

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