Creative thingking skills constitute one of the essential 21-st-century competencies that need to be developed from elementary school, yet science and social studies (IPAS) instruction in the field is stilldominated by lecture method, which positons students as passive listeners. This study aims to analyze the effect of the brainstorming method on student creative thingking skill in IPAS learning for sixth-grade elementary school students. The study employed a quantitative approach with quasi-experimental design in the form of a nonequivalent control group design. The research subjects consisted of 63 sixth-grade students at SDN 1 Weru Lor, divided into a control class of 31 students receiving conventional instruction with the brainstorming method. Data were collected through an essay-based creative thingking skills test constructed from Torrance’s four indicators, namely fluenc, flexibility, originality, and elaboration, administered as a pretest and posttest, supported by teacher and student observation sheets assessing the implementation od the brainstorming method. Data analysis include descriptive statistics, the Shapiro-Wilk normality test , the Levene homogeneity test, the Wilcoxon Signed Rank Test, N-Gain analysis, Normality of N-Gain and Mann-Whitney U test. The result showed that mean pretest-posttest score of the control class increased from 59.45 to n65.68, while the experimental class increased from 63.75 to 83.09. The mean N-Gain of the control class was 16.43 % (low category), while that of the experimental class was 58.72 % (moderate category) The Mann-Whitney U test on N-Gain yielded a significancevalue of 0.000 <0.05. Thus there was significant difference in the improvement of creative thingking skills between students who received instruction using the brainstorming method and those who received conventional instruction. The brainstorming method was proven to be a viable alternative teaching method for improving students creative thingking skills in IPAS learning at elementary school level.
