Abstract:

This study evaluated the impact of a debate intervention on students’ critical thinking. The design-based research project included a quasi-experimental, one group pre-test, post-test design. Results indicated small effect sizes on critical thinking using the Cornell Critical Thinking Test-Level X (d = 0.40) and an assessment of argument analysis (d = 0.41). High-ability students en-tered the project with stronger critical thinking than general-education stu-dents (d = .82; d = .41), and high-ability students appeared to benefit more from the intervention as the performance gaps increased in the post-test phase (d = 1.08; d = .80) suggesting possible aptitude-treatment interactions or the Matthew effect. Qualitative data indicated that students learned to (a) think on the spot, (b) analyze arguments, (c) see other perspectives, and (d) construct counter-arguments. This study corroborates previous research that indicated a relationship between high ability and critical thinking.

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