Identification and remediation of student difficulties with quantitative genetics.
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Date
2006
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Abstract
Genetics has been identified as a subject area which many students find difficult to
comprehend. The researcher, who is also a lecturer at the University of KwaZulu-Natal,
had noted over a number of years that students find the field of quantitative genetics
particularly challenging. The aim of this investigation was two-fold. Firstly, during the
diagnostic phase of the investigation, to obtain empirical evidence on the nature of
difficulties and alternative conceptions that may be experienced by some students in the
context of quantitative genetics. Secondly, to develop, implement and assess an
intervention during the remediation phase of the study which could address the identified
difficulties and alternative conceptions.
The research was conducted from a human constructivist perspective using an action
research approach. A mixed-method, pragmatic paradigm was employed. The study was
conducted at the University of KwaZulu-Natal over four years and involved third-year
students studying introductory modules in quantitative genetics. Empirical evidence of
students' conceptual frameworks, student difficulties and alternative conceptions was
obtained during the diagnostic phase using five research instruments. These included:
free-response probes, multiple-choice diagnostic tests, student-generated concept maps,
a word association study and student interviews. Data were collected, at the start and
completion of the modules, to ascertain the status of students' prior knowledge (prior
knowledge concepts), and what they had learnt during the teaching of the module
(quantitative genetics concepts).
Student-generated concept maps and student interviews were used to determine whether
students were able to integrate their knowledge and link key concepts of quantitative
genetics. This initial analysis indicated that many students had difficulty integrating their
knowledge of variance and heritability, and could not apply their knowledge of quantitative
genetics to the solution of practical problems.
Multiple-choice diagnostic tests and interviews with selected students were used to gather
data on student difficulties and alternative conceptions. The results suggested that
students held five primary difficulties or alternative conceptions with respect to prior
knowledge concepts: (1) confusion between the terms variation and variance; (2)
inappropriate association of heterozygosity with variation in a population; (3) inappropriate
association of variation with change; (4) inappropriate association of equilibrium with
inbred populations and with values of zero and one; and, (5) difficulty relating descriptive
statistics to graphs of a normal distribution. Furthermore, three major difficulties were
detected with respect to students understanding of quantitative genetics concepts: (1)
students frequently confused individual and population measures such as breeding value
and heritability; (2) students confused the terms heritability and inheritance; and, (3)
students were not able to link descriptive statistics such as variance and heritability to histograms. Students found the concepts of variance and heritability to be particularly
challenging. A synthesis of the results obtained from the diagnostic phase indicated that
many of the difficulties and alternative conceptions noted were due to confusion between
certain terms and topics and that students had difficulty with the construction and
interpretation of histograms. These results were used to develop a model of the possible
source of students' difficulties. It was hypothesized and found that the sequence in which
concepts are introduced to students at many South African universities could be
responsible for difficulties and alternative conceptions identified during the study,
particularly the inappropriate association of terms or topics.
An intervention was developed to address the identified difficulties and alternative
conceptions. This intervention consisted of a series of computer-based tutorials and
concept mapping exercises. The intervention was then implemented throughout a third year
introductory module in quantitative genetics. The effectiveness of the intervention
was assessed using the multiple-choice diagnostic tests and interview protocols
developed during the diagnostic phase. The knowledge of the student group who
participated in the intervention (test group) was compared against a student group from
the previous year that had only been exposed to conventional teaching strategies (control
group). t-tests, an analysis of covariance and a regression analysis all indicated that the
intervention had been effective. Furthermore, an inductive analysis of the student
responses indicted that most students understanding of the concepts of variance,
heritability and histograms was greatly improved.
The concept maps generated by students during the remediation phase, and data from the
student interviews, provided an indication of the nature and extent of the conceptual
change which had occurred during the teaching of the module. The results showed that
most of the conceptual change could be classified as conceptual development or
conceptual capture and not conceptual exchange. Furthermore, it seemed that conceptual
change had occurred when considered from an epistemological, ontological and affective
perspective, with most students indicating that they felt they had benefited from all aspects
of the intervention.
The findings of this research strongly suggest an urgent need to redesign quantitative
genetics course curricula. Cognisance should be taken of both the sequence and the
manner in which key concepts are taught in order to enhance students' understanding of
this highly cognitively demanding area of genetics.
Description
Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.
Keywords
Quantitative genetics--Study and teaching (Higher)--KwaZulu-Natal., Concepts., Comprehension., Remedial teaching., Curriculum planning., Science--Study and teaching., Theses--Genetics.