Dissection as an Instructional Technique in Secondary Science: Comment on Bowd

Roger Lock 1
University of Birmingham, England

Bowd (1993) 2 identifies three broad aims for secondary science teaching. I broadly endorse these. I would like to give my perspective on how work with animals, including dissection, is consistent with current secondary school practice in England.

Firstly, the use of dissection as a technique to enhance the acquisition of fine manipulative skills has long been abandoned. Gone are the times when students would carry out multiple dissection of rats, frogs or dogfish (sharks) in order to develop dissection skills for a practical examination. Gone too is the sole use of dissection as a means of studying the anatomy of animals and relating their structure to function.

It is much more common now for animals to be dissected and used first for an investigation directed towards an understanding of the process of scientific enquiry, Bowd's first aim, before going on to be used in an exploration of anatomy, although the two may be closely linked. I will explain.

In England the term dissection is exclusively used in relation to the cutting up of a dead animal or plant or parts thereof; so a 17 year old student, provided with a dead rat, might first use that animal in an investigation of gut enzymes. Where is protein digested in the gut? Where are the products of protein digestion absorbed in the gut? In approaching such an investigation the student could carry out chromatography on the contents of different sections of the gut. The findings from such an investigation could lead to questions about how the structure of the gut in the areas where protein is digested/absorbed is adapted to the function it performs. Such questions could lead to further dissection and macroscopic as well as microscopic observations. Other such investigative approaches involve an exploration of variation in blood sugar levels in different vessels or of the variety of gut movements. Having carried out such investigations, the student could then go on to a more conventional approach to dissection, exploring the gross structure of the digestive, urinogenital and other organ systems.

I concur with Bowd's statement that there is limited data with respect to students' emotional reactions to dissection and other such issues. However, my own work in association with a variety of colleagues does focus on similar areas and in the following I draw comparisons between our and his data.

Similar work carried out in the UK with 14-15 year old students (n=468) suggests that about half (56% females, 48% males) had experience of dissection in their secondary schools (Lock & Millett, 1991). As are Bowd's Canadian findings, this data is retrospective, but the degree of retrospection is much less ­ varying from 1 week to 1 year. It suggests a wider acceptance by teachers in England of students' rights to opt out of lessons involving dissection.

Of the students who had experienced dissection in the UK study, few had dissected whole animals and where they had, these were limited to rats, mice, fish, locusts, stick insects and hens' eggs. The more common dissection experience in England is that of abattoir materials (separated organs) which is offered (but not required) in many schools (Adkins and Lock, in press).

When students were asked in an open question format why they thought animals or parts of animals were cut up to study science in schools a range of reasons were expressed (Lock and Millett, 1992) (Table 1).

The great majority of students in the UK sample can see clear reasons for doing dissection even if some of them are not correct (needed for GCSE ­ an examination taken at 16 or for further education) and, generally, there would appear to be a very positive response.

However, when students in the same sample who had done dissection were asked what they had learned from the experience, a large number responded by saying "nothing," with more females than males expressing this view (Table 2).

Proportionately more males reported that they had learned about the structure and function of the organism involved. The "squeamish" response was reported by the more fastidious students in the sample. This data suggests that where teachers do present students with dissection they need to consider carefully what they expect students to gain from the experience and to structure the work so that such outcomes are made explicit. Alternatively, it may be that the data reflect the scepticism that many students have about the value of such work.

Bowd (1993) found a broadly stable emotional reaction to dissection, whereas other work (Kellert and Westervelt, undated) shows a change with age on similar controversial issues relating to animals. UK data (Lock and Millett, 1992) suggests a wide range of feelings about dissection with some clear differences between the attitudes of males and females (Table 3).

Overall, more females than males feel that dissection is unnecessary or wrong. More males than females have neutral feelings or don't know. Considerably more than the 27% indicated by Bowd show a negative attitude towards dissection.

Like Bowd, I feel it is important to distinguish between an objection to dissection based on moral grounds as contrasted with squeamish feelings. In some other work (Lock, in preparation) I have explored pupil reaction to a peer's objection to dissection on moral or squeamish grounds. Findings indicate that students are supportive of objections on moral grounds but not for squeamishness. Males who are squeamish are prone to derogatory responses from their peers and particularly their male peers. There are sound reasons for helping students to overcome a squeamish response, not least that they might be better able to help in first aid contexts.

Clearly, the data presented in Table 1 suggest that far more than Bowd's 19% of students are offered voluntary participation in dissection in English schools. However, about 50% of pupils do expect teachers to encourage them to participate in dissection (Lock, in preparation) to the point where the form of "encouragement" used might involve coercion, threat or sanctions. More recent work, (Alderman and Lock, in preparation) suggests that few teachers would go to such lengths.

Bowd quotes the British Veterinary Association as if they are an authority on school science in the UK. Few teachers know of this organization which has no influence on dissection practice in UK schools.

No evidence is presented with respect to animals for Bowd's third aim for secondary science teaching ­ the influence of science on societal issues and values. Work in the UK (Lock & Millett, 1992) has explored student views of the ways in which animals are used in research education and farming.

This and other data suggest that students are less supportive of the use of animals in testing cosmetics than they are of using animals in medical research. They are more supportive of using animals in educational and farming contexts (Lock 1993). In general, males are more likely to condone and support the use of animals in all contexts than are females.

There is evidence that the attitudes that students have to the use of animals in research and farming are based on severely limited and, in some cases, inaccurate knowledge. Often attitudes are not supported by behavior (Lock, 1993). In my view, an approach to such a dilemma lies in the production of curriculum materials that inform students, provide them with a balanced range of opinions, both for and against vivisection, and then invite them to discuss the issues and make up their own minds. Such materials are now available in the UK (Lock, 1992).

Bowd raises the issues of the effectiveness of dissection as a teaching strategy. There is only very limited guidance relating to this. I know of no superior alternatives to dissection and disagree with Bowd on this issue. My gut reaction is that there is no substitute for first hand, personal experience and that this is the key to the most effective teaching and learning. I do accept that students who have a moral objection to dissection should be offered alternative approaches and I also think that discussion of the issue should be carried out before using dissection in class.

Bowd asserts that dissection is ineffective, contrary to basic goals and easily replaced. He presents no evidence on which to base such assertions. 3

It is clear to me that there is a wider sensitivity among teachers in England to the dissection issue but it is also clear that there is a need for much more detailed and rigorous research both in North America and Europe.

Notes

1. Correspondence should be sent to Roger Lock, School of Education, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.

2. Editor's note. The following is Bowd's abstract, for those of you who missed the original article:

This article examines the role of dissection in the teaching of secondary biology and environmental science, within the context of the development of attitudes toward animals. Retrospective data concerning their experience in high school with dissection for 191 (Canadian) undergraduate education students are described, and their reported use of alternatives to invasive animal study are evaluated in relation to specific educational objectives in secondary science. It was found that most students were required to perform dissections, that many but not most experienced negative and stable emotional reactions, and that teachers employed limited alternatives to dissection in their classes. The implications of this for secondary science teaching and for teacher education are discussed.

3. Editor's note. The following are references from the growing body of evidence on the issue of the relative pedagogical effectiveness of traditional animal-based laboratory curriculum and alternatives:

Cohen, P. & Block, M. (in preparation). Replacement of lab animals in an introductory-level psychology laboratory course: A validation study.

Leib, M. J. (1985). Dissection: A valuable motivational tool or a trauma to the high school student. Thesis, Master of Education, National College of Education.

McCollum. T.L. (1987). The effect of animal dissections on student acquisition of knowledge of and attitudes toward the animals dissected. Doctoral Dissertation, University of Cincinnati.

Smeak, D.D. (1989). Simulator/media based teaching of basic surgical skills. Proceedings of the first annual International Foundation for Ethical Research workshop, Denver.

Strauss, R.T. & Kinzie, M.B. (1991). Hi-Tech alternatives to dissection. The American Biology Teacher, 53 , 3, 154-157.

References

Adkins, J. and Lock, R. (in press). Using animals in secondary education: A pilot survey. Journal of Biological Education .

Alderman, P. and Lock, R. (in preparation). Practice with respect to dissection in secondary schools .

Bowd, A. (1993) Dissection as an instructional technique in secondary science: Choice and alternatives. Society and Animals, 1, 1, 83-88.

Kellert, R. and Westervelt, M. (undated). Children's attitudes, knowledge and behaviour towards animals: Phase 5 . U.S. Department of the Interior, Fish and Wildlife Services, Washington, D.C.

Lock, R. (1992). Animals and Research. In Stringer, J. (Ed.) Society and technology in science . Box 3, Book 5. Association for Science Education, Hatfield, England.

Lock, R. (1993). Use of animals in schools: Pupil knowledge, experience and attitudes. In Cowie, J. (Ed.) Ethical issues in biomedical sciences: Animals in research and education . Institute of Biology, London.

Lock, R. (in preparation). High school students' attitudes to dissection and using animals in research.

Lock, R. and Millet, K. (1991). The Animals and Science Education project 1990-91 . Research Report. University of Birmingham, England.

Lock, R. and Millet, K. (1992). Using animals in education and research: Student experience, knowledge and implications for teaching in the National Science Curriculum. School Science Review , 74 , 266, 115-123.

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