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Laboratory work is the hallmark of education in science and technology based fields. In the laboratory students can explore their understanding of the subjects being taught by placing their learning in context. Students can also be motivated to learn in the laboratory context if they can feel a spirit of excitement when investigating a scientific phenomenon, or when creating something that actually works. Many of us can remember an occasion where a laboratory class was particularly memorable or enlightening. We can also probably remember many hours of tiresome exercises which seemed to teach us very little. The design and delivery of laboratory classes and the forms of student assessment used in them, need to be examined critically for their contribution to effective student learning.
There is much agreement in the literature on the following range of goals for laboratory work (Ramsden, 1992; Boud, Dunn, and Hegarty-Hazel, 1989):
At the same time as reaching some agreement on the potential goals for laboratories, there is also much agreement that only sometimes is the potential of laboratories fulfilled. The following problems have been highlighted in the literature (Boud, Dunn, and Hegarty-Hazel, 1989):
There are several different ways of presenting laboratory work and they differ greatly in purpose and degrees of student autonomy. In order of decreasing teacher control and increasing student autonomy, these are controlled exercises, experimental investigations and project work. The differences can be recognised using the simple but sound scheme in Table 1 which analyses the level of openness for scientific enquiry in different laboratory exercises (adapted from Herron, 1971; Boud et al, 1989)
|Type of laboratory||Level of enquiry||Definition of level||Material||Method||Answer|
|Structured investigations||2||Given||Given all or part||Part given or open||Open|
Table 1: A Way of Reflecting on Student Laboratory Exercises
These are activities which are wholly designed by the teacher and are often thought of as verification exercises. They can be completed by a student within a short timespan, typically one or two laboratory periods. There is a known outcome and if students follow the instructions, they should arrive at that outcome (more or less).
They can provide introductory experience with the materials and processes of a discipline, equipment, apparatus, organisms, and chemicals, as appropriate. In many disciplines, the whole procedure has become very well honed. Teachers who wish to use controlled exercises with their students can often locate suitable experiments in laboratory manuals from their own student days, in commercial texts, or in discipline-specific education journals. For faculty, a major appeal of using controlled exercises is the ease of finding them and the charm of their predictability. They can be used from year to year with minimum fuss.
A major disadvantage is that students often do not like controlled exercises very much, finding them dull and tedious. Students may not be very sympathetic towards the elegance of exercises nor regard their lab work as a microcosm of experimentation. They can find the pre-lab work a meaningless ritual, the introductory talks and the controlled exercises as lacking personal satisfaction or connection to their world. Results and reports from students in previous years are often readily available and there is the temptation for the task of writing up to become one of 'faking good' the results.
An example of a controlled exercise which students found boring and alienating is the following from a materials science lab where students are expected to learn about the properties of polymers; specifically how polymers behave under different conditions. The students are asked to conduct a series of tests to explore the properties of polymers. They are given samples of a specific size established by standards and asked to test them in tension using a tensile testing machine. Usually they would not do the tests themselves, but watch whilst a technician conducts the tests. After the samples of a range of polymers have broken, the students are required to calculate the basic properties of each material. An assignment is to write the experiment up, with the emphasis being on presentation and producing results of the right order of magnitude. In all, there is little or no opportunity for the students to engage with the techniques or to relate the exercise to their world.
By contrast, the following is an example of a controlled exercise which students found more engaging. It is on the same topic, how polymers behave under different conditions.
Students are asked to test the bouncing power of squash balls at different temperatures, including first dropping them into liquid nitrogen. One student described it as an experiment which he found useful and which captured his imagination. He said the students had fun and got a physical feel for the glass transition temperature and its relation to mechanical properties. Here the squash balls are something that most students recognise. Both the balls and the use of liquid nitrogen have about them an element of drama. Students are asked to do the tests themselves rather than watching someone else and are required to show their results to their demonstrator.
This term is used to cover a wide variety of teaching methods which foster deep approaches to study by encouraging students to take personal initiative in the performance of the exercise. This might range from experimental design, choice of variables for investigation, choice of materials or methods, choice of methods of data analysis, through to choice of the problem for investigation. The investigation would usually be limited in time and scope and would not qualify as a project. Thus, it might be an extension of a controlled exercise which appealed to the student, or a variation of a well-known theme or method. Experimental investigations can be more or less structured - and often this means shorter or longer.
Structured investigations retain teacher control of materials or methods whilst giving students an opportunity for enquiry. Unstructured investigations retain teacher control of the aim but allow students to plan the materials and methods. In practice, experienced teachers can do much to anticipate students' needs in the laboratory and avoid situations where unforeseen or unreasonable demands are placed on the technical support system.
The first is the opportunity to allow students to practice skills of scientific enquiry, such as planning part or all of an experiment, whilst the second is the provision of a good motivational context. The two are linked: planning requires students to invest some personal initiative, and a sense of ownership and initiative is likely to be motivating. In the laboratory setting, it would seem that independent learning, project work, and experimental investigations share the qualities of independence and student motivation, but with decreasing freedom for independent learning.
Interviews with students show that they are very aware of the freedom for independence and of its effects on their motivation: the key to running successful investigations with junior students is not to throw them in from the deep end but to help them proceed from an adequate base of knowledge and skills. The idea of learning cycles is well described in the literature (e.g., Atkin and Karplus, 1963) and is further discussed in Boud et al. (1989).
Why are controlled exercises retained as traditional fare? When do the disadvantages of investigations outweigh the advantages? Costenson and Lawson (1986) interviewed teachers and proffered a list of the top 10 teacher perceptions which have prevented the introduction of enquiry-oriented curricula into junior courses, or have resulted in this type of curriculum being discarded. Any faculty member introducing an investigative approach in undergraduate laboratory work might take note of which of these views they have heard expressed by colleagues.
The issues at the heart of this worry list need to be seriously addressed although sometimes such views are based more on perceived threat, prejudice or conservatism rather than rationality and evidence. Two important factors in improving the successful running and institutionalisation of a program of investigations are teamwork and staff development.
As an example of an experimental investigation, this one allows for more investigation than the controlled exercises discussed above, but is still on the same topic - how do polymers behave under different conditions? In this investigation, the students are given a series of different polymers, a few different testing apparatus and temperature controlling devices. The students are then asked to design an experiment which will explore the viscoelastic properties of polymers. There are many different possibilities including producing a stress/strain plot at different strain rates or temperatures, or by exploring stress relaxation, and these possibilities use the same basic equipment as before. Each student then produces a different piece of work, there can be no copying, and each feels as if they have done something useful. There is no right answer but a feeling of having discovered what the concept of viscoelasticity is all about. It can be related to a real life issue such as investigating the properties of a polymer for use in skis, which need to be used at different strain rates and temperatures.
Done as a structured investigation, the students are given ready-made test pieces from which they select the polymer and decide on the test conditions. As an unstructured investigation, students decide what test pieces are required and either make them themselves or ask the workshop staff to prepare them. They decide on the test conditions and plan accordingly.
Projects are major pieces of work which are intended to simulate elements of real-life research and development activities. It is usually necessary to devote significant periods of time to projects, likely to be from a few weeks to a semester or even one or two years of an undergraduate course. Project strategies are devised whereby students can apply prior knowledge to new problems, and, in doing so, to integrate various manual, technical, and enquiry skills in one coherent activity. Important characteristics are that the research problem must be a new one (where the student's experimental work and results could be seen as a genuine attempt to contribute to scientific knowledge) and that the student carries out the work in a research setting where there would be access to research supervisors or team leaders (in an apprenticeship role, with a potential mentor).
Historically, participation in research projects was the common mode of students working in science courses, but concerns of cost and convenience gradually led to the reservation of research projects for postgraduate students and the use of controlled exercises for undergraduates. However, since the mid-1970s, there has been a widespread return to the use of projects with undergraduates. This seems to be a recognition of the need for students to be involved in intrinsically interesting, personally involving activities which are true to the nature of a science discipline (Bliss, 1990; Bliss and Ogborn, 1977; Dowdeswell and Harris, 1979; Ogborn, 1977).
Benefits of project work are many. The learning is individualized and students are likely to find their project a unique experience. Students are encouraged to accept responsibility for a piece of work and to build up some commitment to the scientific endeavour; they get the satisfaction of working on a sustained task and the opportunity to enhance their oral and written communication skills.
Conceptually, the disadvantages of projects are few - they seem ideally suited to students enhancing their technical, enquiry, and many other skills within a holistic experience. Practically, projects can be risky. The initial choice of a problem may be misguided, practical problems can result in overruns of time, energy, and cost, and the supervisory relationships may not work well. In short, with the scale of project work, there is great need for careful planning by staff to ensure that the experience is a worthwhile one for each student.
While final year projects can draw on students' earlier undergraduate experiences, projects can be usefully employed in any year. They can be used from first year on with a degree of freedom suitable to the students' stage of preparation. An example is the projects which have been trialled with second year mechanical engineering students at the University of Sydney for the subject of 'materials selection'. During these projects, amongst other things, the students learn about polymer properties referred to in the examples of controlled experiments and experimental investigations given above. In essence the project is similar to problem based learning, where students are asked to solve a problem and by solving it they learn new facts and ways of thinking. Students in this case were asked to form materials selection teams working for a large engineering company. In their teams they were asked to choose a structural object and to decide on the best material from which to make it. They might choose a crash helmet or a sailing boat hull, for example. They have to back up their choice with real evidence, ie tensile tests relating the strength of the material to the load it must withstand, toughness tests which relate to the impact loads (eg hitting your head on the road!) to which the object will be subjected, etc. Students also need to know the latest cost of the material and of production.
Each student or group is therefore actually conducting the exercise which materials technologists would do in an engineering company in order to select the best material for a particular application. Students write up a report to the company manager to see if their idea is acceptable. Based on the evidence they provide and their argument, backed up by literature, they are given the commission, or they get a good mark! The whole project lasts three to four sessions of 3 hours per session.
Before considering assessment for a laboratory class, teachers need to consider a set of aims and objectives for the lab and the subject overall which lead to desired outcomes in student learning. These will be the knowledge, skills and attitudes which you would like the student to achieve, rather than a series of factual contents. Once these have been established it is possible to design an assessment scheme which will ensure that you are testing for those attributes. For example, it has been found that if an assessment task is to 'write up the lab' and no guidance is given, students are most likely to reproduce what they did (or possibly what last year's students did!). They are unlikely to reflect on why they did the experiment and what they got out of it unless they receive specific prompts and guidance.
It should also be possible to use the assessment scheme that you devise as a way of both finding out what the students have learnt, and feeding back information to the students about how they are learning and how they might improve their learning. For example, showing reports written by previous students who approached their learning with understanding, or offering feedback on draft reports before final submission. You could go further by involving the students in the process of developing suitable criteria for assessment and in critiquing outcomes in relation to criteria.
Providing you have clear statements of the subject and course objectives and a clear indication of which objectives should be met in students' lab work, your assessment can be directly linked to criteria. Criterion referenced testing simply means being able to select valid objectives for laboratory work and being able to specify the criteria by which successful performance would be recognised. For example, objectives in the polymer lab investigation described earlier are as follows:
For any objective, there is usually a choice of assessment methods, some of which are illustrated below.
The use of a range of appropriately chosen assessments should help students to understand the assessable goals of the subject (ideally, these are the most important goals), encourage students to take a serious approach to their lab work, and be suitably rewarded. In general it is helpful to be sensitive to any gender or cultural influences that may make one type of assessment more accessible to one group than another, and to provide practice assessments where necessary.
An example of a written report with a difference is a case where students were asked to produce a user's guide for a materials selection lab class. The guide provides results of the experiments performed in the lab, together with data from references. Having tested the mechanical properties of a series of polymers or metals, etc, students create a user-friendly guide giving values of modulus, ultimate tensile strength, examples of stress/strain behaviour, etc which they have measured or collated. This helps students to realise the application of such a lab exercise and the student may refer to the guide in years to come to give a ball park figure for data. A material may then be selected for further analysis for a particular design, based only on this preliminary data.
Anecdote suggests that fudging of laboratory assessments is very common. An important point is that almost all of this fudging occurs in controlled exercises - much less occurs in investigations and projects. It is as though fudging is a part of a certain culture where students take no ownership in their work and where matching a pre-ordained right answer is more important than anything else. Below is a series of hints on discouraging fraudulent practice:
Often the person 'demonstrating' the lab class is not the same as thelecturer or designer of the lab. The following issues specifically relate to the person actually teaching in the lab session itself.
Knowledge base: Questions known to concern demonstrators are as follows:
Showing expertise. Being on top of the subject matter, being well prepared for the lab, being familiar with the ideas of the subject, the design of experiments, the use of equipment. Making it clear what has to be done and understood and why; making clear explanations about the ideas, material, and activities; using assessment methods which are valid and reliable; and giving students prompt and high quality feedback on their work.
Meeting students where they are in their learning. Find out where the students should be and where they are in their learning of this topic. Supervising students closely enough to recognize those having difficulties with the concepts on which the laboratory exercises are based. Checkout understanding. Showing encouragement and empathy. Giving students positive feedback and encouraging them to note their own achievements. Providing adequate opportunities for students to practice their skills and to receive precise feedback.
Fostering student independence and growth. Supporting students warmly when they are in high challenge situations; encouraging active participation by students; and avoiding having them stand around in an observational capacity in the lab.
Enhancing student learning. Emphasizing critical thinking, problem-solving, aspects of scientific enquiry, and other intellectual activities which require the students to think. Encouraging students to focus on the integration of the practical exercises with the learning of material taught in other components of the course. Encouraging students to have a lively understanding of the interplay of theory and methodology in the laboratory.
Facilitating not lecturing. Trying to avoid telling students the facts but helping them to find them out themselves by asking questions etc.
Respecting students. Demonstrating respect for each student as a person; valuing diversity; demonstrating a positive attitude and teaching free of discrimination or stereotyping of students because of gender or ethnicity; and monitoring student groupings in the lab and the nature of classroom interactions to bring out the best in each student.
Sharing enthusiasm and making laboratory work an enjoyable experience for students. Finding ways for love of the subject to come across to students, helping make the students' work relevant, interesting, stimulating, and challenging. Being friendly, helpful, and available to the students. Using humour and other techniques for fostering an enjoyable, relaxed, and non-stressful atmosphere in the laboratory. Being a good role model for students.
Monitoring all aspects of the design and delivery of the lab class will help with subject improvement - for ideas on evaluation see the guide in this series Evaluating a Materials Course by Ivan Moore. It is always difficult to make changes to a subject and a large amount of time spent on monitoring will be wasted if it is not possible to implement the recommended changes once they have been deemed necessary. However, it is never a waste of time to know what it is that is most effective for your students learning and to optimise this as much as possible within the imposed constraints.
Atkin, JM and Karplus, R (1963) Discovery or invention? Science Teacher, 29, pp45-51