Teaching in the Laboratory: 1 – Pedagogy

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Overview

The post is the first of two parts of a Resource Pack that I am developing to share with practitioners like myself and is designed to provide information on teaching laboratory practicals in undergraduate science courses. In doing so it draws on the substantial amount of literature dedicated to this topic as well as innovative practices used by practising academics. It aims to provide information for readers new to practice or experienced practitioners interested in changing anything from a single practical, a suite of practicals associated with a module, right through to a change in laboratory teaching philosophy of an entire degree programme. The first section looks at background literature, while the second part will look at applications in practice.

SECTION 1: An overview of pedagogic considerations for the teaching laboratory

Introduction

Why do we teach in the laboratory? The process is so embedded into an undergraduate science curriculum that as practitioners we rarely stop to consider the benefits and opportunities of this environment. As a component of a module or a programme, laboratory teaching can consist of up to 40% of class contact time, but repeated analyses of practical classes indicate that apart from some notable exceptions, little effort has gone into changing the laboratory curriculum over the last 50 years. We can sometimes see this when we teach our students practicals that we may have completed in our own undergraduate studies.

In addressing the question, why do we teach in the laboratory, we, as practitioners, usually list three significant reasons (among others). The first is that science is a practical-sourced discipline; most innovations and understandings of our current knowledge of science is derived from experiments of our predecessors and experiments we, as practising researchers, complete in the lab every day. In teaching a student to be a scientist, we must teach them how to conduct pratical work in the lab. A second commonly reported reason is that it confirms the theory delivered in lectures – students have a chance to test out some principles, reactions or other material covered in lectures for themselves. The great experimenter, Faraday, reportedly said that he “was never able to make a fact his own without seeing it”. A third reason is that it gives students an opportunity to develop their skills in writing a scientific report. The weekly/regular reports students write allow them to develop their report writing skills in writing what they have done, summarising their results and presenting their findings in the context of the greater scientific body of knowledge in the form of a discussion.

These reasons are valid, and based on the notion of educating students to be professional scientists but in the 21st century laboratory, are they enough? The landscape of education has changed so dramatically in the last 20 years, with very many more students completing a wider range and type of degree programme and pursuing a multitude of career paths, many of which are not laboratory based.

While the title of this resource is laboratory education for the 21st century, problems with and limitations of the current most common laboratory teaching method have been highlighted in work reaching far back in to the 20th century. Two reviews by Hofstein and Lunetta, (1982, 2001) have questioned the perceived benefits from laboratory work in its current form. Other significant critics of the traditional approach in laboratory teaching are Meester and Maskill (1995) and Alex Johnstone (Johnstone and Al Shuaili, 2001). The excellent book, Teaching in Laboratories, was written 25 years ago and champions laboratory teaching methods that might be considered innovative, at least not the norm in today’s teaching (Boud, Dunn, Hegarty-Hazel, 1986). There is no shortage of evidence of significant shortcomings of the traditional methods of teaching in the literature, nor of innovations on how to redress the balance.

What follows in this Resource is an argument that it is possible to address the education of scientists pursuing a laboratory based science career through innovative techniques while giving these students as well as students who do not pursue such a career a much wider variety of learning experiences and outcomes in their laboratory programme. This is achieved through the use of innovative teaching practices (such as those exampled in Section 2) in this valuable, expensive learning time and space in their degree programmes. In short, I offer a win-win scenario!

Laboratory Teaching Approaches

Table 1 summarises the four main teaching approaches in the laboratory, taken from Domin’s work (1999). By far the most common method is the expository or “recipe-style” laboratory, where students complete a procedure given in the laboratory manual to deduce from their data a pre-determined outcome (what a colleague has referred to as “the answer in the lecturer’s jacket pocket”!). As such, from students’ perspective, these laboratory practicals have a “pass/fail” theme to them in that students either get the right answer or make the right product, or don’t. This limits the opportunities for genuine reflection (Domin, 1996).

Table 1: Laboratory instruction styles according to their outcome, approach and procedure (Domin, 1999)

Style

Descriptor

Outcome Approach Procedure
Expository Predetermined Deductive Given
Inquiry Undetermined Inductive Student Generated
Discovery Predetermined Inductive Given
Problem-based Predetermined Deductive Student Generated

This teaching method is so prevalent most likely because of its ease of delivery to large numbers of students and lower costs of operation. It can be argued that it mimics a work-based environment (e.g. following a standard operating procedure. Alternative methods of instruction are in the main much rarer. With the exception of the student project in their final year, it is not uncommon for students to have completed their entire practical programme in the expository style.

Questioning the Current Approach

Perhaps because of its prevalence in the science education landscape, the expository or “recipe-style” lab has been subjected to much analysis and criticism by science educators. Anecdotally, most practitioners could come up with some reasons why. It has already been mentioned that these labs focus on (from the students’ perspective) the right answer. How many manual instructions finish with the words “Compare your answer with the known value and comment on any difference”? As educators, we know what we mean here – we want the students to consider the variety of factors involved in any experiment and quantify their impact on the final result, an important process of reflection on the experiment demonstrating an understanding of the underlying theory and the experimental process. For students, it reads “did I get the right answer and if not what did I do wrong?” Students can get quite demoralised as they very often do not get the “right answer”, which leaves them with the often wrong impression that they are not good at lab work. The process of reflection does not run much deeper than that.

A second observation from teaching in laboratories arises when the teacher asks the student what they are doing, or a more involved question, why they are doing a task. Very often, the answer is along the lines of I am doing what it says on line 3 of the manual and I am doing it because it says to do so on line 3.

Thirdly, considering anecdotal observations, the assessment of laboratory work focuses on a weekly laboratory report. It is a strange irony that practical work assessment does not usually assess practical work.

It is no surprise then to find that these criticisms of the expository style, along with some more based on pedagogic points given below, are validated by a very large body of analysis in the science education literature. Hofstein and Lunetta state that

the recipe-style labs used in most institutions do not allow for the student to think about the larger purpose of their investigation and of the sequence of tasks they need to pursue to achieve those tasks

and that

assessment is seriously neglected, resulting in the impression that lab; work does not need to be taken seriously”.

Because of their structure, these labs do not challenge the students higher order cognitive skills. An analysis of ten commercial laboratory manuals found that they contained activities requiring the use of the lower half of Bloom’s cognitive domain (knowledge, comprehension, application) (Domin, 1999b).  Similar results were found for UK university chemistry laboratory manuals (Meester and Maskill, 1995) and UK first-year chemistry practicals (Bennett, 2000).

In addition to the structure of an expository lab, Johnstone has argued that they present a significant cognitive challenge to students. In a typical three hour practical period, students are required to process a large amount of oral and textual information, recall theory and prior skills and then process and analyse results (Johnstone Sleet and Vianna, 1994). The authors argue that given this large amount of information processing required, it is unsurprising that students “intellectually opt out and use the manual as a recipe book”. The nature of the expository lab, and in particular its assessment method, facilitates this approach.

Assessment and Learning Outcomes

Before proceeding to the second section of this Resource, it is worth considering what we want students to get from a laboratory education. This in turn should be followed by mechanisms to effectively assess these outcomes. Several researchers have detailed the learning outcomes of practical work and these are presented in Table 2. In addition, researchers have investigated the nature of outcomes that are specific to the expository style and those which are addressed by alternative styles. A point that will be taken up in Section 2 of this Resource is that the nature of the assessment should be more varied in order to effectively align the assessment with the wide variety of outcomes potentially achievable from practical work.

Table 2: Potential learning outcomes of practical work, and the teaching method that can effectively address them; the assessment should address the outcome (italicised)

Outcome

Expository

Other

Manipulate apparatus and instruments Yes Yes
Perform routine techniques Yes Yes
Collect and process data Yes Yes
Interpret data after the experiment Yes Yes
Communicate findings in the form of a report Yes Yes
Solve problems through experimentation Yes
Design an experiment to test a hypothesis Yes
Effectively work as part of a group to address a large problem Yes
Consider safety aspects of laboratory work Yes
Disseminate findings in an appropriate manner to a variety of audience types Yes

Summary of Section 1

Laboratory practical classes deservedly have a central role in science education but the method of delivery warrants a substantial rethinking in order to deliver best possible outcomes for students and staff given the expensive time and input involved. While the traditional method of teaching is suitable for instrumental training and reporting of data, these skills could be similarly addressed using other more innovative techniques, which would have the added value of resulting in additional learning outcomes such as group work, experimental planning and alternative methods of dissemination.

The level of new material presented in each class in the traditional teaching style also challenges students as they may not be able to process the amount of information and therefore resort to “following the recipe”. The nature of verification/production style procedures mean that students aim for a right answer, and miss out on valuable opportunities to reflect on the implementation and process of the experiment.

In section 2, several strategies and examples are presented which aim to show the reader how they may change their teaching practice to take into consideration the issues discussed here.

Image Credit: Chemical Heritage Foundation on Flickr

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