The effect of GASING with teaching at the right level on third-grade students' critical thinking in addition

Abstract

Critical thinking remains a fundamental competency that has yet to be optimally developed in elementary mathematics education, particularly when instructional approaches fail to account for differences in students’ cognitive readiness. This study aims to examine the effect of integrating the GASING method (GAmpang, aSyIk, nyeNGkan) with Teaching at the Right Level (TaRL) on the critical thinking skills of third-grade elementary school students in addition learning. A quasi-experimental design with a non-equivalent control group was employed, involving 88 students divided into a control group (n = 43), which received GASING instruction, and an experimental group (n = 45), which received instruction integrating GASING and TaRL. Critical thinking skills were assessed based on students’ abilities to analyze quantitative relationships, justify mathematical reasoning, and evaluate problem-solving strategies using an eight-item analytical rubric with a maximum score of 24. Before the intervention, both groups had relatively comparable baseline scores, as indicated by the Welch’s t-test (t(78.85) = 1.445; p = 0.152). Improvements in critical thinking skills (Gain_CT) were analyzed using an independent-samples t-test after testing for normality using the Shapiro–Wilk test and homogeneity of variance using Levene’s test. The results showed that the experimental group achieved a significantly higher mean improvement than the control group (M = 44.60 vs. M = 24.65; t (86) = −4.640; p < 0.001; Cohen’s d = 0.99), indicating a large effect size. These findings suggest that structured, reasoning-oriented instruction combined with ability-based cognitive differentiation can support the development of critical thinking skills among students with diverse ability levels. This study provides empirical evidence of the importance of diagnostic assessment as a foundation for designing elementary mathematics instruction and highlights the potential of adaptive learning in developing higher-order thinking skills.