MEDICAL EDUCATION

A Controlled Trial of Peer-Teachingin Practical Gross Anatomy

J.O. NNODIM*

Department of Anatomy, Faculty of Medicine, University of Benin, Benin City, Nigeria

The present study is an evaluation of a peer-teaching program in practical gross anatomyinvolving 80 volunteer second-year medical students. They were assigned 20 per cadaver, butdivided into two subgroups of 10 each. The subgroup which dissects during a given sessionwould demonstrate their accomplishments to the other subgroup at the commencement of thenext dissecting session, before withdrawing to study independently. The other subgroup wouldthen proceed to dissect during the rest of the session and, on the next practical day, demonstratetheir work to their peers in the complementary subgroup. Thus, each subgroup performed onlyhalf of the 36 work units on the trunk, relying on their peers for instruction on the other half.Eighty students with similar entry-level qualifications were selected from the rest of the class toserve as controls. Their student-to-cadaver ratio was also 20:1 but every member was inattendance at all dissecting sessions. In the experimental and control programs, each studentwas actively engaged in dissection for an average of 5.4 hours.

A 200-item two-choice theory paper and a 50-station practical test comprising specimen-based questions were administered at the end of the study. Students in the peer-teachingprogram performed significantly better than their full-time dissecting counterparts. Thepeer-teaching program was well-received by the students: it reduced the crowding at dissectingtables considerably and offered them opportunities to hone their communication skills. Thenon-dissecting time was also much-valued and well-utilized. Clin. Anat. 10:112–117,1997 r 1997 Wiley-Liss, Inc.

Key words: self-directed learning; cooperative learning; dissection; demonstration

INTRODUCTION

In a traditional preclinical anatomy curriculum,dissection tends to be the dominant learning mode interms of time allocation. At the University of BeninMedical School for instance, exactly half of the 648hours assigned to anatomy is devoted to studentdissection. The educational returns, however, appearto be incommensurate to the investment in time, andstudent dissection has been criticized in a number ofstudies (Sinclair, 1965; Holt, 1976; Bachop, 1986) forreasons which include the health risks involved inworking with formalinized specimens and the fact thatmany students actually do not dissect. The latter isespecially true in institutions where the student-to-body ratios are high.

A comparison of students at the University of BeninMedical School who studied from prosections withthose who dissected showed that both groups per-formed equally well on testing, inspite of the fact that

the former had spent only 74% of the time utilized bythe latter (Nnodim, 1990). This parity remained de-monstrable after 5 years (Nnodim et al., 1995). How-ever, less than a third (28.6%) of the students recom-mended that dissection be dispensed with altogether.Instead, a drastic curtailment of the dissection pro-gram was endorsed by the majority.

The present investigation evaluates a leap-froggingscheme of practical work in the gross anatomy of thetrunk in which two groups of students dissectedalternately (i.e., half the time). Each practical sessionbegan with one group demonstrating to the other, on

Contract grant sponsor: U.S. Educational Commission for ForeignMedical Graduates, contract grant number 92M006.

*Correspondence to: J.O. Nnodim, Department of Anatomy andCell Biology, The University of Michigan Medical School, 4643Medical Science II Building, Ann Arbor, MI 48109-0616.

Received 19 September 1995; revised 1 March 1996

Clinical Anatomy 10:112–117 (1997)

r 1997 Wiley-Liss, Inc.

the specimen, the structures they had exposed andstudied during their own turn at dissecting (i.e., theprevious practical session).

MATERIALS AND METHODS

A total of 160 second-year medical students partici-pated in the present study during 1993–1995. Therewere two sets of volunteers, each comprising 40students, and these constituted the experimental group.For each set, 40 students with similar Joint Matricula-tion Examination (JME) scores were selected from therest of the class to serve as controls. Apart fromgeographical considerations, performance at the JMEis the main criterion for admission into university inNigeria and was used in the present investigation as anindex of general academic ability. All groups also hadthe same gender composition: 14 males, 6 females.

The topographical region studied during the pro-gram was the trunk (thorax and abdomen). Prior tothis, the upper limb had been dissected by the entireclass in the traditional manner (see below). As a result,the experimental groups were acquainted with bothmodes of practical work at the end of the study and sowere in a position to make valid comparisons betweenthem.

Traditional (Control) Program

The practical work on the trunk was divided into 363-hour sessions. Twenty students were assigned toeach cadaver, and during practical classes, they tookturns playing two active roles: one member readingaloud from a manual and another carrying out thedissection and demonstrating to the rest of the group.Each student got to dissect for a total of 5.4 hours onaverage.

The investigator spent about 15 minutes with thestudents during the final hour of each session, review-ing with them the structures exposed and drawingattention to points worthy of special note. Otherteachers circulated among the tables at other times.

Peer-Teaching (Experimental) Program

The student-to-body ratio in the experimental pro-gram was also 20-to-1 but at each table, the partici-pants were divided into two subgroups (Alpha andBeta) of 10 students each.

Ahead of the first practical class, one of the sub-groups (Alpha in Fig. 1A) prepared the first unit ofwork in the manual (Bones and Joints of the ThoracicCage). At the first session, they gave a demonstrationof the subject to the other subgroup (Beta in Fig. 1A)on an articulated skeleton for about 30 minutes. Themembers of the demonstrating subgroup took turns

pointing out the features of interest and leading thediscussion. Thereafter, they withdrew to reading roomsin the department or to the library for independentstudy while subgroup Beta embarked on Unit II.

At the second practical session (Fig. 1B), subgroupAlpha had Unit II (which they would not dissect)demonstrated to them by subgroup Beta, before pro-ceeding to tackle Unit III. Thus, both subgroups ateach table leap-frogged through the program, each onedissecting only during alternate practical sessions (i.e.,half the number carried out by the full-time dissectingcontrol groups). As with the control groups, the dissect-ing subgroups were visited by the investigator forabout 15 minutes towards the end of the session, andother teachers were accessible to them at other times.The investigator also moderated the first couple ofdemonstrations, but subsequently was unbiased interms of the attention paid to the experimental andcontrol groups. Each student in the experimentalprogram actively dissected for the same length of time(5.4 hours) as his/her counterpart in the traditionalgroups.

The experimental and control groups listened tothe same formal lectures and watched the same films.

Assessment and Analysis

Two tests: a 200-item theory paper and a 50-stationpractical test, with specimen-based questions at eachstation, were exhibited at the end of the program.Each of the 40 questions in the theory paper consistedof a stem and five items. The students were required

Fig. 1. A scheme illustrating the changing roles of the subgroupsat an experimental table during the first three practical sessions.

Peer-Teaching in Gross Anatomy 113

to consider each item with the stem and to respondwith ‘‘true’’ or ‘‘false’’ (Harden, 1979). The items ofthe theory paper were drawn from a repository ofquestions shown by previous analysis to possess satis-factory facility and discrimination (Lipton and Hux-ham, 1970). Wrong answers were ‘‘fairly’’ counter-marked as per the Glasgow scheme (Harden et al.,1969).

Student’s t-test was used to evaluate the differencesbetween the scores gained by the control and experi-mental groups. The latter were requested to submitcomments on the program.

RESULTS

The scores gained by the participants in the theoryand practical tests are set out in Table 1. Students inthe peer-teaching program performed significantlybetter than their traditional counterparts in the two-choice paper (57.5 6 20.5 vs. 46.8 6 22.4; P , 0.05).Their scores in the practical test were also higher butthe difference did not reach significance at the 5%level (60.0 6 13.1 vs. 55.2 6 18.6; P . 0.05).

The responses proffered by the experimental groupto issues raised in the debriefing questionnaire, includ-ing a sampling of their free comments, are set out inTables 2 and 3.

DISCUSSION

The inspiration for the present study was drawnfrom the University of Michigan Medical Schoolwhere a peer-teaching program in practical grossanatomy was instituted in the fall of 1992 to providestudents with ample unscheduled time for indepen-dent learning. At the University of Benin, it is envis-aged that such a program will serve an additional andmore compelling purpose: that of decongesting thedissecting tables. Like in all medical schools which donot enjoy the benefit of willed bodies, student-to-cadaver ratios are very high (20:1 for the class studied).This ratio was halved by having the students work intwo rotating shifts, thus creating an atmosphere moreconducive to active participation in dissection. Over-

all, each student in the peer-teaching groups spent thesame number of hours dissecting as did his/her tradi-tional counterpart.

Inspite of the documented evidence suggestingthat students might still learn gross anatomy ad-equately if they did not have to dissect by themselves(Sinclair, 1965; Bulmer et al., 1982; Nnodim, 1990;Nnodim et al., 1995), especially under circumstancesof extreme difficulty in obtaining sufficient cadavermaterial, dissection remains a required learning activ-ity for preclinical students in Nigerian medical schools(National Universities Commission, 1989). Further, asizeable number of students continue to express awish for dissection to be retained in the curriculum(Besag et al., 1976; Nnodim, 1990), presumably be-cause it is the one course component that mostdistinctly sets them apart from all other undergradu-ates in the university during the preclinical years. Theprogram described in the present study meets the twinobjectives of liberating time for autonomous studentlearning and enabling them to dissect as much as theywould do under the traditional arrangement.

According to Sinclair (1972), practical classes inanatomy are not only opportunities for hands-on learn-ing, but also a forum at which students discuss amongthemselves and assist in each other’s education. Bothlearning approaches thus operate simultaneously inthe gross anatomy laboratory setting, and identicalutility indices were computed for them in a study ofstudent preferences of learning methods (Nnodim,1988b). A peer-teaching program therefore is, in asense, a consolidation of these two mutually reinforc-ing learning modes.

The superior performance of the students in theexperimental program in the theory test indicates thatthey were better informed, almost certainly becausethey had more time to themselves for self-directedlearning. A number of studies (Besag et al., 1976;Nnodim, 1988b) have shown that students obtain mostof their anatomical knowledge through reading andprivate study. Accordingly, they can reasonably beexpected to exhibit more knowledge in tests whenmore time is made available to them for learning inthis way. To the extent that scores in National Boardexaminations measure learned anatomy, Yeager andYoung (1992) remarked that their students comparedwell with their counterparts nationally over a 12-yearperiod of peer-teaching in gross anatomy.

The experimental program was well-received bythe participants, as judged by the majorities who votedthat it was adequate for their learning needs (77.3%),and should even replace the traditional arrangementeither completely or to some extent (90.9%). Overtwo-thirds (68.2%) expressed satisfaction with the

TABLE 1. Test Scores (%)*

GroupTest

Theory*,* Practical

Experimentala (n 5 80) 57.5 6 20.5 60.0 6 13.1Traditional (n 5 80) 46.8 6 22.4 55.2 6 18.6

*Values given as mean 6 standard deviation.*,*Difference between groups statistically significant (P , 0.05).aPeer-teaching group.

114 Nnodim

quality of the dissections and their presentation bytheir peers. The negative comments made seemed toderive more from a suspicion of what could happen(e.g., ‘‘structures might be misidentified or displacedfrom their natural positions’’; ‘‘incorrect informationmight be accepted as otherwise’’) rather than actualexperiences. The impression of the investigator andother instructors was that the students in the experi-mental group were no more necessitous of facultyintervention than those in the traditional program. Allambiguities were clarified during the visit of theinvestigator towards the end of the dissecting session.

The majority (89.5%) used their non-dissectingtime well and the most heavily subscribed learningactivity was reading/private study (71.4%). Unfortu-nately, the options available to students at the Univer-sity of Benin in terms of self-instructional resourcesare very meager: plastic and wet, potted museumspecimens; books; and charts. Many students cited theprovision of more and a wider variety of these re-sources as a measure to enhance independent study,but the perennial underfunding of tertiary educationimposes rather narrow limits on how much improve-ment is achievable in this context.

Other demerits mentioned were that they were ‘‘toomuch on their own’’ and that some participants wereinclined to behave disruptively. They might be reflec-tive of the relative youthfulness of our medical stu-dents and the teacher-centered character of theireducational experience: respects in which they differfrom their American counterparts who are graduates ofuniversities and liberal arts colleges. All but one of theparticipants matriculated into university directly fromsecondary school (equivalent to high school in theUnited States) and their average age was 19.4 years(range: 17–24 years). A tendency to be unserious,perhaps more than once in a while, is not altogetherincompatible with such a level of immaturity.

The formal didactic lecture and other similar teacher-driven learning activities which do not guaranteelearning for every student (Nnodim, 1988a; Arm-strong, 1991) are hallmarks of the local educationculture at all levels. Because the information dis-pensed is usually the basic amount required to passexaminations, many students continue to insist on theregimentation of their education by their teachers andfail to develop independent learning abilities. Forsure, it is more the educational system than the

TABLE 2. Experimental Group Responses to Debriefing Questionnaire

Proposition/questions Responses1

1. During the peer-teaching trial just concluded you carried out only half of the dissections.How adequate was this arrangement for your learning needs? Very adequate 27.3)

Just adequate (50.0)Inadequate (9.1)Very inadequate (2)No opinion (13.6)

2. Half of the dissections were carried out by your peers and demonstrated to you.a) How adequate were their dissections? Very adequate (13.6)

Just adequate (54.6)Indifferent (18.2)Inadequate (13.6)

b) How beneficial were their demonstrations? Very beneficial (31.8)Beneficial (36.4)Average (27.3)Not beneficial (4.5)

3. You were at liberty to commit 50% of the time for practical gross anatomy to whateveracademic purpose you chose.

a) What learning activities did you engage in? Reading (71.4)Discussions with peers (46.4)Examining museum specimens (35.7)Examining histology slides (10.7)Discussions with lecturers (10.7)

b) How well do you think you used that time? Very well (15.8)Well (73.7)Not so well (10.5)Totally wasted (2)

4. Do you think peer-teaching should replace the traditional program of practical work ingross anatomy? Yes—Completely (13.6)

Yes—To a great extent (72.8)Yes—To a small extent (4.5)No (9.1)No opinion (2)

aPercentages in parentheses.

Peer-Teaching in Gross Anatomy 115

students that is culpable in this regard, since the latterset great store on private study (Nnodim, 1988b) andare likely to respond favorably if taught the appropri-ate skills.

Unlike the program at St. Louis University (Yeagerand Young, 1992), no saving in faculty time, coursehours, or cadavers is realized by our scheme. Neverthe-less, the benefits enumerated by the students (Table3) make an impressive list.

A workshop is being designed to introduce studentsto problem-based learning on the Barrows model(Barrows, 1985) which embodies active, independent,self-directed study techniques. Such exposure will setthe stage for the fruitful exploitation of the results ofthe present trial in terms of its possible adoption on aclass-wide scale, or as a parallel option for whichstudents may volunteer.

The educational virtues of student dissection areundeniable and, in institutions possessing sufficientamounts of the requisite resources, its conduct in thetraditional format can hardly be faulted. However,drawbacks exist in less well-endowed settings and theconcerns raised by them deserve to be addressed. Thepresent study has sought to evaluate a remedialstrategy along those lines.

ACKNOWLEDGMENTS

I am grateful to the United States EducationalCommission for Foreign Medical Graduates for theaward of a Foreign Faculty Fellowship (92M006)which enabled me to spend my sabbatical year (1992/1993) at the University of Michigan Medical School,Ann Arbor. My sincere thanks are due to ProfessorBruce M. Carlson, my Fellowship Director, and Profes-sor Bill Burkel for arranging my participation in thegross anatomy program at Ann Arbor, during which theidea for the present study was conceived. I alsoacknowledge my debt of gratitude to the students whovolunteered to join me in trying out something newand different.

REFERENCESArmstrong, E.G. 1991 A hybrid model of problem-based learn-

ing. In The Challenge of Problem-Based Learning. D. Boudand G. Feletti (eds.). London: Kogan Page, pp. 137–149.

Bachop, W. 1986 Minimizing risks and maximizing benefits inthe gross anatomy laboratory. Trans. Illinois Acad. Sci.79:279–282.

Barrows, H.S. 1985 How to Design a Problem-Based Curricu-lum for the Preclinical Years. New York: Springer PublishingCompany, 148 p.

TABLE 3. Selected Student Comments

Context Comment

Merits of peer teaching ‘‘It affords me time to spend as I choose.’’‘‘My reading has become more profound.’’‘‘I have the opportunity to catch up and stay current.’’‘‘The requirement to educate others has sharpened my attention

during dissection and challenged me to work harder.’’‘‘I am able to learn from others by exchanging ideas with them.’’‘‘I am able to find out what is in textbooks other than my own

without having to read them.’’‘‘I get a measure of myself relative to others.’’‘‘I have become better at expressing myself verbally.’’‘‘I learn more and better when I discuss the topic.’’‘‘I am able to ask questions freely.’’‘‘On the days that I dissect, I am too physically exhausted to study

at night: such days were reduced by half.’’Demerits of peer teaching ‘‘Nil.’’

‘‘Some students are sometimes unruly, unenthusiastic, and unco-operative.’’

‘‘Whatever the demerits, they are outweighed by the merits.’’‘‘We were too much on our own.’’‘‘Structures may be misidentified or displaced from their natural

positions.’’‘‘Incorrect information may be accepted as otherwise.’’‘‘It is discontinuous.’’‘‘One is tempted to be lazy.’’

Measures to improve the learning effectiveness of peer teaching ‘‘Fewer students per group.’’‘‘More learning resources to facilitate private study.’’‘‘Formal discussions should be arranged during non-dissecting

time.’’‘‘Assignments should be given.’’‘‘Stricter monitoring by lecturers.’’‘‘Very important work units to be demonstrated by faculty.’’‘‘Frequent tests to keep us on our toes.’’

116 Nnodim

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