Using variation theory to enhance students' capability in solving pedigree problems

Abstract

This thesis reports on a learning study that employed variation theory to enhance a domain-specific generic-capability pedigree analysis of Hong Kong secondary five students so as to help them develop their capability to solve pedigree problems. Pedigree analysis is a study of inheritance in genetics, which includes the deduction of dominant and recessive characters. The literature and local examination reports suggested that solving pedigree problems is difficult for students, as the process of deduction demands conceptual understanding and use of scientific language. Three biology teachers participated in this learning study using variation theory. Teachers shifted the focus of lesson observation from teaching performance to student learning, to how students deduced the dominant character from pedigree problems, which was the object of learning. To explore the effectiveness of such teaching and learning to solve pedigree problems through different patterns of variation, two cycles of learning study were conducted in two senior biology classes. Results showed that students were more able to deduce the dominant character with relevant genetic principles by experiencing the variations. Both conceptual understanding and scientific language are critical aspects of solving pedigree problems. This study also suggests that explanatory scientific writing needs to be broken down into different components and then differentiated patterns of variation designed to let students discern those components and their relationships; in that way their writing can be ‘scaffolded’ in a stepwise manner rather than giving them the whole writing framework at once. However, the identification of critical features and patterns of variation and their relevance to the object of learning should be considered carefully and explored further.