Challenge-based learning (CBL) is a student-centered approach engaging learners in complex, open-ended problems. While such openness can foster deeper learning and creativity, it also demands high self-direction. Teachers must therefore provide sufficient scaffolding without undermining CBL’s authenticity. This study examines how secondary education teachers design and enact scaffolding in sustainability-oriented CBL projects, and how students experience this support. A multiple-case study of three projects distinguished soft scaffolding (adaptive, just-in-time support) from hard scaffolding (predefined tools and structures). Data included teacher interviews (n = 3), student focus groups (n = 18), and classroom observations. Findings showed the scaffolding type and function depended on project open-endedness, teacher readiness, and alignment with project focus. In the most open-ended project, the teacher mainly used soft scaffolding to guide thinking and decision-making, whereas more structured projects relied on hard scaffolds for procedural support. Students’ experiences varied: some thrived under autonomy, developing ownership and engagement, while others needed more explicit guidance. These results suggest that scaffolds should align with project goals, be explicit in their contribution to progress, match students’ readiness for self-directed learning, be enacted by teachers comfortable in a coaching role, and include affective support to help students manage frustration and uncertainty.

Quizzing before (pretesting) or after (posttesting) studying is effective for learning, but via different underlying mechanisms: Posttests require students to actively recall information; pretests highlight knowledge gaps about the material. Instructional videos allow for studying these strategies because, unlike text‐based materials, they are generally delivered at a fixed pace. Hence, this study investigates when pretesting, posttesting, and corrective feedback are most effective when learning from instructional video. Employing a between‐subjects design, 223 secondary school students watched a video and completed no quiz (control) or a quiz before (pretest) or after (posttest) viewing, with half of them receiving immediate feedback. Students' retention performance and self‐regulated learning (monitoring and regulation) were assessed. Results showed that quizzing enhanced learning from instructional video only for quizzed items and primarily when incorrect responses were followed by feedback. Quizzing improved regulation but not monitoring. These findings underscore the importance of carefully implementing quizzes in video‐based instruction.

In today’s rapidly changing world, societies are confronted with complex problems spanning environmental, social, and economic dimensions, placing increasing demands on education to prepare student...