<![CDATA[Critical thinking, written communication, and collaboration are essential competencies in biology education, yet students often have difficulty applying them to contextual ecological problems. This study examined the effect of ethnoscience-based Problem-Based Learning that integrates the Lampung Tupping tradition on these three competencies. A posttest-only quasi-experimental design with intact, nonequivalent groups involved 74 Grade X students selected through cluster random sampling from a population of 297 students. The experimental class (n = 37) received ethnoscience-based PBL for three meetings (9 × 45 minutes), whereas the control class (n = 37) received conventional instruction on the same ecology content. Critical thinking and written communication were measured using validated essay tests with Cronbach’s alpha coefficients of 0.671 and 0.623, respectively; collaboration was assessed using a structured observation rubric. MANOVA showed a significant multivariate group effect: Pillai’s Trace = 0.945, F(3, 70) = 400.455, p < 0.001. The experimental class outperformed the control class in critical thinking (M = 88.35, SD = 3.90 vs. M = 60.22, SD = 5.37; mean difference = 28.14; partial η² = 0.902), written communication (M = 81.76, SD = 11.26 vs. M = 56.62, SD = 10.93; mean difference = 25.14; partial η² = 0.569), and collaboration (M = 89.27, SD = 5.72 vs. M = 55.03, SD = 5.60; mean difference = 34.24; partial η² = 0.904). The culturally contextualized problems enabled students to connect ecological concepts with local knowledge, construct evidence-based written explanations, and negotiate solutions collaboratively. These findings support integrating local wisdom into biology curricula and teacher professional development while recognizing the study’s short duration and single-school context.]]>
