2026 IJRSE – Volume 15 Issue 20
Available Online: 22 August 2026
Author/s:
Altez, Florence B.
Don Mariano Marcos Memorial State University, Philippines (faltez@dmmmsu.edu.ph)
Abstract:
This study examined the effectiveness of an Activity-Based Electronic Strategic Intervention Material (E-SIM) in improving Grade 9 students’ problem-solving performance in solving oblique triangles. A quasi-experimental, non-equivalent group pretest-posttest control-group design was employed with 40 Grade 9 students from a public secondary school in Candon City, Philippines. Twenty students received the Activity-Based E-SIM, while 20 students received conventional paper-based remediation addressing the same competency. The intervention integrated guided learning activities, interactive tasks, multimedia resources, practice exercises, assessment activities, enhancement tasks, and reference materials designed to support the application of the Law of Sines and Law of Cosines. A researcher-developed 72-point problem-solving assessment was administered before and after the intervention. Descriptive statistics, paired-samples t tests, an independent-samples t test of gain scores, and analysis of covariance (ANCOVA) were used to examine within- and between-group differences. Both groups demonstrated significant improvement from pretest to posttest: the control group increased from M = 18.20 to M = 61.10, t (19) = 35.22, p < .001, while the experimental group increased from M = 18.10 to M = 63.00, t (19) = 36.86, p < .001. Although the experimental group obtained a greater mean gain (44.90) than the control group (42.90), the difference was not statistically significant, t (38) = 1.16, p = .253, d = 0.37. Similarly, ANCOVA showed no significant adjusted posttest difference between groups, F (1, 37) = 1.31, p = .261. The findings indicate that both instructional conditions were associated with substantial improvement, but the study did not establish a statistically significant advantage of the Activity-Based E-SIM over conventional remediation. The study highlights the potential of activity-based electronic materials as supplementary resources for competency-focused mathematics remediation while emphasizing the importance of instructional alignment, structured practice, and appropriate comparison conditions.
Keywords: activity-based learning, electronic strategic intervention material, E-SIM, mathematical problem solving, oblique triangles, trigonometry, Grade 9 mathematics
DOI: https://doi.org/10.5861/ijrse.2026.26385
Cite this article:
Altez, F. B. (2026). Activity-based electronic strategic intervention material for Grade 9 students’ problem solving in oblique triangles: A quasi-experimental study. International Journal of Research Studies in Education, 15(20), 37-54. https://doi.org/10.5861/ijrse.2026.26385