GUIDED DISCOVERY LEARNING SEBAGAI STRATEGI PENINGKATAN KEMAMPUAN PEMECAHAN MASALAH MATEMATIS SISWA: KAJIAN KUASI-EKSPERIMEN

Mathematical problem-solving skills among Indonesian junior high school students remain a persistent concern, as reflected in low PISA 2022 achievement and preliminary observations showing that most seventh-grade students at SMP Islam Bustanul Hikmah Lamongan struggled to devise and execute solution strategies. Teacher-centered instruction relying on lectures and repetitive drills was identified as a contributing factor, limiting students' active engagement in constructing mathematical understanding. This study aimed to examine the effectiveness of the guided discovery learning model in enhancing students' mathematical problem-solving ability on the topic of scale, compared to conventional instruction. A quasi-experimental method with a pretest-posttest control group design was employed, involving 32 students in the experimental class and 30 students in the control class, selected through purposive sampling. Data were collected using a validated essay test based on Polya's four problem-solving indicators and analyzed through normality, homogeneity, independent sample t-test, and N-Gain procedures. Results indicated that the experimental group's posttest mean (78.44) significantly exceeded that of the control group (65.67), with the independent t-test confirming a statistically significant difference (p = 0.000). The N-Gain analysis further showed a higher mean improvement in the experimental group (0.58) compared to the control group (0.34), with the most notable gains observed in the indicators of solution verification and planning. These findings confirm that guided discovery learning offers a more effective instructional approach than conventional teaching for developing mathematical problem-solving skills, particularly in applied topics such as scale.