Abstract

• The main purpose of this study was to investigate the Grade Nine students’ mathematical thinking skills in relation to mathematics achievement. A Quantitative research design was used. In this study, total of (397) Grade Nine students from two private schools and two public schools in Mandalay City Development Area were chosen. To collect the data, two instruments: (1) a test for students’ Mathematical thinking skills test based on Lutfiyya’s (1998) some aspects of mathematical thinking and (2) achievement test based on Grade Nine mathematics textbooks, were used. The mathematical thinking skills test included five major aspects: (1) generalization, (2) induction, (3) deduction, (4) logical thinking, and (5) problem- solving skills. In the analysis of data, one-way ANOVA, independent samples t-test, and Pearson product-moment correlation were used. According to the results, there were no significant differences in the mathematical thinking skills of Grade Nine students in terms of gender and type of school. Moreover, the results revealed that there was no significant difference in the mathematics achievement of Grade Nine students in terms of gender but a significant difference in terms of type of school. Furthermore, the result of the present study showed that Grade Nine students’ mathematical thinking skills were significantly and positively related to their mathematics achievement and the strength of correlation was typical (r=.367). It can be concluded that students who have highly mathematical thinking skills tend to have higher mathematics achievement test scores. Therefore, this study made a positive contribution to the development of mathematics education in Myanmar.