Evaluating Grade 10 learners’ change in understanding of similar triangles following a classroom intervention

Abstract

Geometry, in particular Euclidean geometry, has been highlighted as a subject in mathematics that presents a variety of challenges to many secondary school learners. Many students struggle to gain appropriate knowledge of geometrical ideas as well as to display solid reasoning and problem-solving abilities. Mathematics educators, parents, and the government, represented by the Department of Basic Education (DBE), have all expressed worry over students' poor performance in Euclidean Geometry. The purpose of this study was to evaluate Grade 10 learners’ changes in the understanding of similar triangles following a classroom intervention. This study explored the following main research question: How can a classroom intervention be designed to improve Grade 10 learners’ understanding of similar triangles? The study followed the social constructivism paradigm since learners should learn under a cooperative learning method to construct conceptual knowledge. The van Hieles’ model assisted the researcher to determine and identify Grade 10 learners’ geometric level. Furthermore, participatory action research was employed because the researcher was part of the study, responsible for the teaching design. The study adopted a mixed method design. A qualitative approach used the following instruments to collect data: an intervention, observation, and semi-structured interview. Eight (8) participants contributed to the qualitative data and were chosen via purposeful sampling to determine their understanding. These data were subjected to analysis. The quantitative approach used baseline test and the post-test as data collection instruments. The population consisted of (43) FET band learners who chose mathematics as an area of study at a Secondary School. The baseline test was used to determine the learners’ present knowledge of geometry considering the van Hieles' levels (VHL). After the designed intervention, the post-test, in comparison with the baseline test, was used to determine the effectiveness of the intervention and the change in understanding of the learners’ concepts of similarity within the topic, geometry. Statistical and descriptive data analysis was deployed to describe the effect of the change. The study shows that the designed intervention was effective, and the results indicate that half of the learners in this group improved in their understanding of similar triangles.