Enhancing Secondary Students' Geometric Thinking and Teachers' TPACK through Lesson Study Incorporating Phase-Based Instruction Using GSP

Abstract

Geometry has in many countries, proved to be one of the topics in mathematics that is problematic for students to understand. This shows that teaching and learning geometry in Thailand has not been very effective because the effective student must come from effective teaching approaches and appropriate use of teaching tools. This study aims to determine the extent to which lesson study incorporating phase-based instruction (LS-PBI) using GSP enhances secondary students' levels of geometric thinking and to examine the changes in secondary teachers’ GSP-TPACK before, during and after LS-PBI using GSP. The quantitative approach utilizing quasiexperimental research design was employed to answer the research question on students' levels of geometric thinking while qualitative approach was employed to answer the research question on teachers’ GSP-TPACK. In this study, five teachers and three groups of mix-ability students in an urban school in Yala province, Thailand were chosen as the research participants. The intervention in this study is phase-based instruction using GSP of five lesson plans in the topic of “Relationship between 2D and 3D geometric shapes” which were carried out in the lesson study cycle. Three groups of students were taught this topic in turn by three different teachers. Pretest and Posttest were employed for assessing students’ van Hiele level of geometric thinking while observation, focus group discussion and individual interview were employed for assessing teachers’ GSP-TPACK. The results show two major conclusions on students’ geometric thinking and teachers’ GSP-TPACK. First, LS-PBI using GSP enhanced secondary students' levels of geometric thinking as xvi expected in the hypothesis testing that there are statistically significant differences in Groups 1, 2 and 3 students' levels of geometric thinking before and after LS-PBI using GSP and also the difference in the levels of geometric thinking among the three groups of students after LS-PBI using GSP. It shows that the initial van Hiele levels of students’ geometric thinking in Group 1, Group 2 and Group 3 were predominantly at level 1 before the intervention and were predominantly at level 3 after the intervention. Besides, the posttest score was greater than the pretest score in every group and students in Group 3 who have learned with the last revised lesson plans got the highest mean score of posttest. Second, the secondary teachers’ level of GSP-TPACK changes from level 0 before LS-PBI using GSP to level 5 after LS-PBI using GSP. Before the intervention, the teachers’ initial levels of GSP-TPACK were at level 0 and level 1. During LS-PBI using GSP, the teachers’ levels of GSPTPACK progressed continuously. After LS-PBI using GSP, the teachers’ levels of GSP-TPACK progressed to level 3, 4 and 5. The findings suggested the effectiveness of LS-PBI using GSP in enhancing both students’ level of geometric thinking and teachers’ level of GSP-TPACK.