Development of inquiry learning-based mathematics teaching materials to enhance critical thinking skills on frequency tables and bar charts for fourth-grade elementary students

The availability of mathematics instructional materials that support the development of critical thinking remains a challenge in elementary education. This study aimed to develop and evaluate Inquiry-Based Learning mathematics teaching materials for fourth-grade students on frequency tables and bar charts, with activities designed to support critical-thinking development. The study employed a Research and Development (R&D) design based on the Plomp model, consisting of preliminary research, prototyping, and evaluation. The evaluation phase included a limited trial with Grade IV-A students and a field trial with Grade IV-B students. Product validity was assessed by mathematics education, Indonesian language education, and practitioner validators using percentage-based validation scores, while practicality was examined through teacher and student response questionnaires and classroom observations. The effectiveness analysis involved a one-group pretest–posttest design with 32 Grade IV-B students and was conducted using a paired-samples t-test, N-Gain, and Cohen’s dz. The teaching materials obtained validity scores of 98.75% from the mathematics education validator, 93.75% from the language validator, and 93.75% from the practitioner validator. Teacher response scores averaged 97.74% across the limited and field trials, while student practicality scores were 78.6% and 75.6%, respectively, both categorized as practical. In the field trial, the mean critical-thinking score increased from 42.13 to 63.53, with a statistically significant pre-post difference, t(31) = 6.387, p < .001. The mean N-Gain was 0.35 (medium), and Cohen’s dz was 1.13, indicating a large standardized pre-post difference. These findings provide preliminary evidence of improvement in students’ critical-thinking performance following implementation of the developed teaching materials. However, because the effectiveness phase used a one-group pretest–posttest design without a comparison group, the observed improvement cannot be attributed solely to the teaching materials. The developed materials therefore represent a promising instructional resource whose potential contribution to critical-thinking development should be further examined using larger samples, longer implementation periods, and comparative or controlled research designs.