RESUMEN
This research aimed to employ stacking and racking analysis techniques in the Rasch model to measure the hydrolysis conceptual changes of students taught by the process-oriented guided inquiry learning (POGIL) model in the context of socio-scientific issues (SSI) with the pretest-posttest control group design. Such techniques were based on a person- and item-centered statistic to determine how students and items changed during interventions. Eleventh-grade students in one of the top-ranked senior high schools in the eastern part of Indonesia were involved as the participants. They provided written responses (pre- and post-test) to 15 three-tier multiple-choice items. Their responses were assessed through a rubric that combines diagnostic measurement and certainty of response index. Moreover, the data were analyzed following the Rasch Partial Credit Model, using the WINSTEPS 4.5.5 software. The results suggested that students in the experimental group taught by the POGIL approach in the SSI context had better positive conceptual changes than those in the control class learning with a conventional approach. Along with the intervention effect, in certain cases, it was found that positive conceptual changes were possibly due to student guessing, which happened to be correct (lucky guess), and cheating. In other cases, students who experienced negative conceptual changes may respond incorrectly due to carelessness, the boredom of problem-solving, or misconception. Such findings have also proven that some students tend to give specific responses after the intervention in certain items, indicating that not all students fit the intervention. Besides, stacking and racking analyses are highly significant in detailing every change in students' abilities, item difficulty levels, and learning progress.
