The Use of Role-Playing Exercises in Teaching Undergraduate Astronomy and Physics

Paul J. Francis, Aidan P. Byrne, PASA, 16 (2), in press.

Next Section: Other Role-Playing Exercises
Title/Abstract Page: The Use of Role-Playing
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Contents Page: Volume 16, Number 2

Subsections



Case Study: Solar System Formation Exercise

The case study is of an attempt to teach the theory of solar system formation, using a competitive role-playing exercise, during lectures.

The aim of this exercise was to attempt to get every student in the class to actively think through what they were learning, right there in the lecture. The challenge was to achieve this while still covering material at the rate achieved in conventional lectures.

This exercise was trialled in the first semester of 1998. It was used on two classes of ANU first-year students. The first class, PHYS1003 `Astronomy and Planetary Science' was designed for students with no background in maths and physics, and had an enrolment of around 50 students. The second class, PHYS1005 `Introduction to Astrophysics' was designed for students with a strong high school maths and physics backgrounds (mainly intending physics majors), and had an enrolment of around 20 students.

Pre-lecture Preparations

The aim of the exercise was to teach students about the processes whereby a giant molecular cloud turns into a collection of stars, with associated planets. This involves the idea of gravitational collapse, angular momentum support of accretion disks, nuclear fusion within the star, and particle agglomeration in the proto-planetary disk. This subject matter would normally have taken 2-3 lectures to cover.

The subject matter was broken into seven distinct pieces, divided by the physical process at work, and each piece was written up as a briefing paper, one page long. One briefing paper, for example, covered the role of gravity in the process of star and planet formation. It described how gravity will cause a gas cloud to shrink, and form lumps of mass $\sim 10^{30}$ kg, which (in the absence of other forces) will continue to shrink, on a free-fall timescale (a number was quoted) until they form black holes. A second paper covered the role of angular momentum: it pointed out that if (for whatever reason) a gas cloud should try and shrink, its rotational speed will increase until centrifugal force balances gravity, which occurs on scales of $\sim 100$ AU. Other papers covered processes within accretion disks, the role of thermal pressure and cooling, condensation of grains, the collision of rocks to form planets, and the ignition of nuclear fusion in stars. The processes were necessarily simplified for a first-year class, but no more so than would have been required in a lecture.

Lecture Preamble

The lecture commenced with a five minute slide show about giant molecular clouds, and about how stars and planets are thought to be born within them. A pre-exercise briefing was then carried out. The students were warned that they were about to take part in a role-playing exercise, designed to give them a feel for how the process of astronomical discovery works in practice.

``Pretend that this lecture is a research conference, and that you are the world's experts on star and planet formation, gathered together to try and figure out how one of these (Malin slide of a giant molecular cloud) turns into several of these (NASA composite slide of sun and planets). Divide yourselves up into groups of three.''

Groups of two or three seem to be optimal for these exercises: any larger and the less articulate group members cease to play any effective part. Each group was given three copies of one of the briefing sheet. To add to the role-playing aspect, each group was also assigned a real astronomical institute from somewhere around the world. We might say, for example:

``You three are experts in gas dynamics, from the University of Cambridge.''

The class was then addressed as a whole again.

``Each group of you are world experts in some branch of astrophysics. Just as in the real world, however, no single group can hope to know enough to solve this difficult problem alone. You will have to exchange information with many other groups to devise a complete picture, and win the undying glory of being first to figure out how stars and planets form. In the real world, whoever figured this out first would win Nobel prizes, fame, tenure, grants: all the good things in life! We cannot offer you that, but instead, whichever group comes up with a correct theory first will win this box of chocolates.

Take a few minutes to read your briefing sheets, and discuss what you have learned amongst yourselves. If you have any questions, come down and bug me. Once you've figured out your own areas of expertise, you will have to go out and exchange information with the other groups. Anything goes; you are allowed to form consortia, lie, cheat, steal, bribe: anything to figure out a complete picture. But bear in mind that unless you share information with other people, they will not share information with you. You are not allowed to show other groups your briefing papers: you must explain what is on them verbally. Your goal is to put all the information you will learn from the other groups together, to make a coherent theory of star and planet formation.

When you think you've figured out a theory that makes sense, complete with numbers and timescales, you must come down the front and present it to the class. The rest of the class will then vote on whether you deserve the chocolate. This, again, is just like the real world: you don't win by getting the right answer: you win by getting an answer that your peers will accept.

Once the exercise is over, I will hand out copies of the combined briefing sheets to all of you, and you will have to write-up the complete theory as part of an assignment. OK: if there are no questions, get going!''

While the Exercise is Running

The initial class response was generally stunned silence. Slowly groups read their briefing papers. Most classes had to be encouraged to start discussing their briefing papers, rather than just reading them individually in silence.

The lecturer then walks around the class, listening in on groups and offering advice, clarification and encouragement. At first, it was necessary to repeat over and over again that:

``You don't know enough to figure this out for yourselves. Go out and talk to some of the other groups, and see if they know anything that helps fill in the gaps in your story''.

Once the first groups had started wandering around the class, accosting other groups and demanding to know what they were experts in, the whole class rapidly got the idea, and broke up into anarchy. Before running this exercise, we were worried that the class might just start gossiping, playing games, or otherwise mucking around, but in practice, this was never the case: without exception students seemed to focus on the exercise. The structure of the exercise was designed to stop groups from opting out of the discussion, as if a particular group was not very active, they would still be accosted regularly by other groups trying to find the answer to some problem, and this seemed to keep everyone continuously involved.

The classes contained one or two very keen amateur astronomers, and initially we were worried that they would know the answers and thus short-cut the exercise. We therefore required students to describe the full process, including timescales, as we doubted that any students could know this. This seemed to work: indeed the most knowledgable students were particularly enthusiastic and commented that the exercise made them see this subject in a whole new light.

It rapidly became clear, from wandering around listening and helping, that certain points were confusing almost all the students. For example, the briefing paper on rotation had described the law of conservation of angular momentum, and how it means that as the cloud shrinks, it must spin faster, until rotation balances gravity. It transpired that many students got hung up on the following question: what happens if the cloud isn't spinning at all to begin with? Why should clouds spin, after all? We had never realised that this would be a sticking point: it was necessary to stop the exercise (by shouting and clapping loudly) and point out to the class that even the tiniest rotation would be amplified by the collapse process, and the odds of anything having absolutely no rotation at all were tiny.

The atmosphere in class was wonderful: lots of excited chatter, students racing around interrogating each other and debating the science. Many of the conversations we listened too really sounded like academics in discussion:

``So, we've got this spinning cloud. What happens next? Is it dense enough to start forming grains, like you said?''

``But won't it turn into a black hole first?''

``Those idiots from Caltech won't share their information with us.''

Once the exercise was up and running, the lecturer proved almost redundant: the students were answering most of each other's questions without reference to me. Indeed, at the end of the lecture, it was difficult to persuade the students to leave.

Ending the Exercise

The students proved reluctant to conclude that they had a complete answer (even when they did), and so it was necessary to encourage the groups that seemed to be close to stand up and present their results. In most cases, the first group to present a theory turned out to be confused about some details, and were voted down by their peers. We were worried that some would take offence at this, so we insisted on a round of applause for their bold try. In practice, however, this did not seem to be a problem.

On the second or third try, a solution was generally reached that the class was comfortable with. The lecturer then summarised it, and reminded the students that they had to write up the complete answer as an assignment. Roughly half a lecture was then spent de-briefing the students: explaining some of the issues that had been glossed over in writing the notes, and pointing out some of the unresolved problems of star and planet formation.

Once the exercise was completed, students were given the full set of seven briefing papers, and required to write-up the full theory of solar system formation as an assignment. These were marked and returned to the students, allowing the correction of any mistaken ideas the students had accumulated.

Good Points of the Exercise

The experiment had a variety of beneficial effects.

  • The exercise was popular with most students. The courses in which these techniques were trialled scored very highly in end-of-semester student assessment questionnaires. Student comments on the anonymous questionnaires included:

    ``I enjoyed the interactive approach to the lectures - they make you think about what is happening''

    ``He (the lecturer) involved the class and made us actively think by explaining things to our neighbours or having class activities which helped reinforce the information''

    ``The most notable strengths of the lectures were the willingness of the lecturer to let us participate in group activities''

  • The exercise (including the follow-up lecture) covered the subject matter at least as rapidly as conventional lectures.

  • Perhaps the greatest benefit was unexpected: the exercise taught the lecturer what the sticking points in student understanding of the course were. Many of these sticking points were very basic and quite unexpected (though generally obvious with the benefit of hindsight).

  • The exercise palpably changed the classroom dynamics: for the remainder of the semester, the class was noticeably more interactive and friendly even in conventional lectures.

Bad Points of the Exercise

  • Many students implicitly assumed that the seven briefing papers were seven jigsaw pieces to be assembled in order. They did not realise that one physical process can occur at multiple points during the star formation process, or that two phenomena can operate in parallel, despite implicit statements requiring this in the briefing papers.

    When this exercise was run for the second time, the students were warned against this tendency towards linear thinking in the lecture preamble. This seemed to fix the problem.

  • The briefing papers contained several `red herrings': statements which while true were not relevant. Students clearly had an implicit faith that anything that was in the notes must be relevant, and so tended to construct convoluted stories of star formation, constructed so as to include all the red herrings.

    Once again, explicitly warning the students against this tendency in the lecture preamble seemed to fix the problem.

  • The exercise took about 75 minutes to run, which did not fit into a single lecture slot. This was a serious problem: when the exercise was resumed in the subsequent lecture, students had lost the thread of argument and were no longer motivated. Wherever possible, these exercises should be simplified sufficiently that they can be run in a single session. A possible alternative would be to run one of these exercises very slowly: perhaps devoting ten minutes per tutorial to it for a month.

  • The lecturer work-load required to prepare this exercise was approximately 50% more than would have been required for a conventional lecture. With experience in the techniques, however, this may decrease.


Next Section: Other Role-Playing Exercises
Title/Abstract Page: The Use of Role-Playing
Previous Section: Educational Theory
Contents Page: Volume 16, Number 2

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