Abstract
The study developed a STEM-oriented mathematics module for fifth-grade students on two-dimensional shapes and examined its quality from the perspectives of validity, practicality, and critical-thinking outcomes. The development process followed the Plomp model, comprising Preliminary Research, Development or Prototyping Phase, and Assessment Phase, with Tessmer's formative evaluation embedded in the prototyping stage. Evidence was collected through expert-validation forms, classroom observations, teacher and student questionnaires, and critical-thinking tests. Content validity reached 96%, media/design validity 97%, and language validity 100%. The mean practicality score was 96.76%. Students' mean critical-thinking score increased from 65.00 on the pretest to 87.50 on the posttest, while mastery increased from 45% to 90%. The N-Gain value of 0.64 indicated a moderate improvement. These results indicate that the module satisfied the criteria for very high validity and practicality and supported improvement in fifth-grade students' critical-thinking performance.
Keywords
mathematics learning module; STEM; 2D shapes; GeoGebra; critical thinking