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3.1.1 - Development of study program and its rationale

The objective was to strengthen the students’ skills in critical reasoning. In this study program, these skills were fostered by students conducting and discussing thought experiments to solve real problems.

What’s the difference between this and a normal question-and-answer tutorial? A normal tutorial discussion tests whether students have understood ideas as conveyed by textbook and/or an academic ‘expert’. Thought experiments on the other hand are fundamentally distinct from this approach; they entertain multiple solutions to test each hypothesis and therefore require the iteration of ideas between students and their tutors. That is, they encourage intellectual engagement by stimulating curiosity and initiative. Thought experiments are the difference between simply understanding current theories and developing the skills and confidence to use this knowledge to make one’s own contributions.

1. Design of the study program

The phases of the study program are set out in Table 1. The course began with an introductory lecture to outline the approach, providing the groundwork to motivate students to take ‘ownership of their own learning’ (Carrigan 2018). The remainder of the course was based on my prepared text, which included both references to key papers and quiz questions. The text was supplemented by tutorials that focused on questions from students prompted by the text and its related material. These together provided the background and ‘lead-in’ for the thought experiment to follow. The questions from students could be either handed in ahead of the tutorial or raised during the tutorial. The final step was the formulation by the tutor and students of the thought experiment to be tackled individually by the students over several days. Optionally, students could hand in their solutions to the thought experiment or could raise them during a tutorial-seminar set for this purpose.

Description of a thought experiment

A thought experiment is the practice of ‘thinking through’ the consequences of a hypothesis ( In this paper, the focus is on testable hypotheses. Section 2.4 gives an example based on a publication by Ullrich and Novacky (1990) concerning ion movements associated with pH regulation.

A thought experiment can take the following form:

  1. A plausible hypothesis (this might be found in the literature or generated by students during tutorials);
  2. The ‘expected’ result might sometimes be observed, but sometimes the opposite might occur, so creating an enigma;
  3. A new hypothesis is developed bringing together concepts to explain the discrepancy in results;
  4. An experiment is proposed to test the new hypothesis and resolve the enigma (the solution).

In practising with these thought experiments the students are encouraged to find their own solutions. After the students feel they have found the solution they are encouraged to formulate a new hypothesis. It is very important to emphasise that in contrast to the more usual ‘question-and-answer’ that test knowledge, students should not aim at a quick answer and then check the solution, or whether they are right: that approach will not develop their critical, innovative thinking. Rather, participants should try hard to find their own solutions, put the problem aside for some days, do some more reading and ponder about the enigma. Then, they often will get the broad outline of the solution in a flash. For example, when they are swimming, walking or having a drink. This insight may show the hypothesis being considered is not sufficient, or on the other hand, that it is worth testing in the laboratory. Only when the participants feel they have a rational solution can they write a statement which can be handed out and discussed during a tutorial / seminar.

There are many general papers on the development of critical thinking and its use in education ( including a seminal paper on cognitive learning and the ‘hierarchy of thinking levels’ by Bloom (1956). Here we have described a plant sciences course focused on developing critical thinking in 3rd to 4th year university students, which is distinguished by its inclusion of thought experiments created by the academic, but also by the students after they have understood the subject and can evaluate the data. At this level, practice of a thought experiment relied heavily on the initiative of students, although more structured guidance might be required for students in the final years of secondary school. Crucially, thought experiments were discussed by the participants during tutorials / seminars, so encouraging them not only to engage in higher level critical thinking but to have the confidence to put forward and debate their reasoning. In my experience posing of questions to be solved by thought experiments has been the key to achieving the independence of the students, with the measure of independence being the expression of innovative ideas, some of which have led to published experimentation (Colmer et al. 1998).

2. Reasons why the study program was developed

Carrigan’s statement quoted above that ‘University teaching is there for people to take ownership of their own learning’ seems so obvious. Yet, it took me years at The University of Western Australia to develop a design that did motivate the students to become independent and skilled in debating their views. To amplify the importance of this change in teaching approach, I give a brief description of the various stages of my University teaching career.

When I started as an Associate Professor in 1968, at the School of Agriculture of The University of Western Australia, my courses were centred on lectures. I used this classical teaching approach even though I had early on read the sage advice of an experienced academic: ‘Before giving a lecture ask yourself if a lecture is really the best way to stimulate the interests of the students’. Fortunately, with time, I became disillusioned with the approach based on lectures. This in particular when I marked examination papers: even the brightest students showed little evidence they really understood the principles taught during the year. The turning point came when one of my students chose a biochemistry course about which he was very enthusiastic. So, I went to the biochemistry lecturer for advice (Dr Patty Weaver, UWA). She also had found her courses based mainly on lectures did not work, so she had developed a mode based on study guides and tutorials. Her explanation is worth recounting in some detail: marking examination papers she found only few principles had been grasped. Then she looked at the exam results of a course of one of her colleagues, who was renowned as an orator. Surprisingly, she found the same dismal results, so she concluded that when even her ‘orator’ colleague failed, lectures would remain ineffective for her and she developed a new type of course. These were based on texts written by herself with references to relevant sections from textbooks and scientific journals. It should be emphasised that tutorials were an integral part of these courses.

I realise the emphasis on the tutorial in teaching is not ‘rocket science’. For a long time, tutorials have been used, among others, by the University of Oxford and the University of Cambridge as a core teaching method (, These tutorials are based around ‘conversations’ between a small number of students and their tutor, a specialist in the topic. The University of Cambridge lists this system of ‘personal tuition’ as one of its greatest strengths ( Closer to home, the benefits of encouraging student ownership of their learning experience have been recognised by The University of Western Australia through its support of a ‘flipped’ classroom model. This model encourages on-line content delivery, with face-to-face in-class time used to engage students in collaborative, complex problem-solving activities (

It is timely to comment here on the use of the internet in teaching. Of course, with the ability to use the internet, the question of whether a classical lecture course is still warranted has become more acute. In my view, so-called self-pacing courses based on scripts on the internet without suitable backup by tutorials are not much better than lectures, and possibly inferior.

Assessment by participants

About 150 students participated in the course I describe here over a 4-year period at UWA, while around 50 participated in workshops in Southeast Asia. Years later at reunions, students continued to rate the courses as a substantial success, with several graduates commenting to me: ‘in your courses you always strived to make us think for ourselves’. I used the same approach during workshops lasting 2 - 3 weeks among others in Southeast Asia. In Thailand, the background of the participants ranged from agricultural college to PhD graduates. The response was most encouraging; students from across these different backgrounds came up with innovative solutions. A visiting English academic commented: ‘We often say it is difficult to get Thai students to talk and express their own views. However, your courses show that need not to be so at all.

The outcome of this type of approach was remarkable. Many students designed astute and sometimes original thought experiments, and tutorials were lively and stimulating, as described in the words of one colleague, Tim Colmer, who experienced this approach as an undergraduate and used it successfully in workshops in Southeast Asia.

Testimonial by Tim Colmer, University of Western Australia

I have been extremely fortunate to have experienced Hank Greenway's teaching style, both as an undergraduate student at the University of Western Australia (third year unit on Environmental Plant Physiology, 1988), and then as a young academic as part of the team assembled by Hank to deliver Training Workshops on Experimental Techniques in Plant Physiology in Thailand (1996) and Vietnam (1997). As undergraduate students, we soon realised that we were experiencing what at that time was an 'unusual approach' - there were only a couple of lectures (to help orientate us), readings from a well-prepared booklet and of a published review, and two tutorials per week. We soon become active learners, bring our questions to the tutorials at which Hank and/or team members from his laboratory would enthusiastically engage us in wide-ranging discussions and encourage us to find answers from our own reading of other literature and increasingly from thought experiments. A highlight was that mid-way through the semester we formed small groups and each group conducted an experiment - designing an experiment to test our own hypothesis - learning about the scientific method and other valuable skills such as team work, critical thinking, data presentation, and the written and oral communication of our results (as well as plant stress physiology). This was an experience that several other graduates still talk about when we occasionally meet and reminisce, as well as being an excellent learning experience and preparation for our final year’s honours research projects.

As a young academic, I enjoyed being part of Hank's team for an Australian Crawford Fund Training Workshop in Thailand. I observed the careful planning; the selection of the pre-reading papers, the workshop booklet, a few key lectures, tutorial discussion topics, and hands-on experiments. A great strength of the approach was to cater for the interests of the participants, within the overall workshop theme of Plant flooding stress. Groups conducted biochemical experiments, studied nutrient uptake, evaluated responses to ethylene, or quantified aerenchyma and root radial oxygen loss. Participants gained theoretical knowledge, applied the scientific method and gained skills in some laboratory techniques. Although the time was short, the experiments produced valuable data sets, and even resulted in a joint publication by one of the groups (Colmer et al. 1998).

The success of the workshop in Thailand resulted in the Vietnamese participant suggesting a similar workshop held in Vietnam. Hank enthusiastically applied for funding again from the Crawford Fund and he organised the Workshop. Unfortunately, a health issue meant that Hank was not able to participate. Tim Setter and I lead the workshop following the 'Greenway Recipe', and once again achieved in-depth discussions, participant-centred learning with various hypotheses and thought experiments discussed, and some experiments conducted by small groups. I have recently been fortunate to meet again each of the main in-country hosts of these two workshops; we reminisced fondly what enjoyable learning experiences we had together and how these had influenced our subsequent careers.


One obvious practical problem can be the scarcity of funding for tutors required when the number of participants is higher than say 12 - 14 (the optimal numbers for a tutorial), and indeed, the design of university education described here was in my experience often quickly dismissed with: ‘there are no funds for tutors’. I was able to overcome this financial hurdle by involving PhD students. During the period in the 1980s when I developed this approach, the PhD students were Brian Atwell, Ed Barrett-Lennard, Miles Dracup and Tim Setter. These students received no stipend for their contribution. Feedback indicated that they felt they had benefitted from the stimulation endowed in guiding the less advanced students, together with reinforcement of their own understanding of physiological principles and their exposure to methodologies to encourage critical thinking in others. More recently, all these contributors have commented that giving these tutorials has benefitted their later careers.

There must be other ways to overcome this financial problem and academics surely should be innovative enough to find solutions, particularly in this new age where in vivo lectures can be readily replaced by on-line presentations (lectures and appropriate texts). As one example, the online textbook ‘Plants in Action’ ( is a free resource available globally, which can be used as suggested reading in the early phases of courses such as the one outlined here.