Feedback complexities interact with prior knowledge

Background: Formative assessment is a promising option for addressing heterogeneity in schools. Hereby, feedback is both a core element of formative assessment and beneficial for learning. Regarding its effectiveness, we already know that elaborated feedback is particularly conducive to learning. However, it is unclear what exactly constitutes effective elaborated feedback. Aims: We investigated the effects of different task-level forms of elaborated feedback, namely feedback based on conceptual or procedural knowledge and knowledge of result feedback on students’ achievement. Sample: Participants were N  = 190 seventh-grade students from seven secondary schools in Lower Saxony, Germany. Methods: We conducted a randomized controlled study in a pretest/posttest design. The participants solved math tasks by adding fractions. After incorrect responses, they received feedback. We randomly assigned them to receive elaborated conceptual feedback ( n  = 48), elaborated procedural feedback ( n  = 46), knowledge of result feedback ( n  = 50), or no feedback ( n  = 46). The no-feedback group was the control group. Results: After controlling for students' prior knowledge, only elaborated feedback was more effective than no feedback, with no significant differences found between the two types of elaborated feedback and the knowledge of result feedback. Additionally, we observed an interaction effect, showing a reduced effect of prior knowledge on student achievement in the conceptual feedback group. Conclusions: These results imply that feedback can address learner heterogeneity, especially in its elaborated form. Hereby, it is especially important for learners with low prior knowledge to receive adequate feedback, as learners with less prior knowledge especially benefit from conceptual feedback.