Blended Problem-Based Learning for Enhancing COVID-19-Related Scientific Understanding and Critical Thinking in Thai Secondary School Students

Abstract

The COVID-19 pandemic revealed substantial gaps in students’ pandemic literacy and created a need for more resilient science education approaches. This study investigated the effectiveness of a four-stage blended Problem-Based Learning (PBL) module on COVID-19 sciences for enhancing conceptual understanding and critical thinking among 133 Thai secondary school students aged 13–15 years. The intervention combined structured online foundational learning through Google Classroom with collaborative hands-on construction of alcohol-based sanitiser dispensers. A quasi-experimental repeated-measures design was used across four assessment points (pre-test, mid-test, post-test, and one-week retention). Conceptual understanding was measured through a 36-item COVID-19, Sanitiser, and Dispenser Conceptual Test (CovSD-CT), while critical thinking was assessed using a rubric across three reasoning dimensions: Purpose, Mechanism, and Context. Mean (M) conceptual scores increased significantly from pre-test (M = 16.56) to post-test (M = 20.54) out of 35 points with a large effect size (Cohen’s d, d = 0.96) and remained above baseline after one week. Critical thinking abilities showed substantial development across all dimensions, with Context reasoning showing the largest improvement (rank-biserial correlation, r<inf>rb</inf> = 0.91) and significant retention gains (r<inf>rb</inf> = 0.81). Purpose (r<inf>rb</inf> = 0.77) and Mechanism (r<inf>rb</inf> = 0.75) reasoning also improved significantly from pre-test to post-test despite greater decline at retention. The blended approach proved particularly effective, with the online phase establishing foundational knowledge and the hands-on phase reinforcing application-oriented understanding. These findings suggest that sequential blended PBL approaches offer considerable potential for pandemic science education while developing essential 21st-century reasoning skills.