Formative assessment (FA), also known as assessment for learning, is understood as an instructional practice in which evidence of student learning is continuously elicited, interpreted, and used to adapt teaching and learning to students’ needs (Cauley & McMillan, 2010). By supporting ongoing instructional adjustment and addressing diverse learning needs, FA has become a central pedagogical approach for promoting inclusive, learning-oriented classroom practices. Within this framework, formative peer and self-assessment (PASA) are regarded as particularly powerful practices, as they actively involve students in assessment processes and extend opportunities for feedback and reflection beyond teacher-led assessment (Black & Wiliam, 2018).

Numerous studies demonstrate that FA enhances both cognitive and noncognitive outcomes, including academic achievement, motivation, self-efficacy, and self-regulation (e.g. Granberg et al., 2021; Rakoczy et al., 2019; Yan et al., 2022). However, evidence from mathematics education also points to mixed effects of FA and PASA on student learning outcomes, which are commonly attributed to variation in implementation quality (Maskos et al., 2025). These findings highlight the pivotal role of teachers, as the learning effectiveness of FA depends largely on how assessment practices are planned, enacted, and used within classroom instruction.

This challenge is further reflected in observational research. FA is often only partially and inconsistently implemented in classroom practice and frequently with limited instructional quality (Buholzer et al., 2020; Gotwals et al., 2015), particularly with regard to PASA. Accordingly, teachers play a central role in FA by interpreting evidence of student learning and using this information to adapt instruction and provide feedback that supports further learning (Narciss et al., 2020). In the context of PASA, professional demands increase further, as teachers are required to design suitable tasks, establish transparent criteria, scaffold assessment processes, and orchestrate classroom interaction (Wanner & Palmer, 2018). Consistently, empirical research identifies teachers’ limited assessment literacy—understood as teachers’ knowledge and skills related to the design, implementation, interpretation, and use of assessment information to support student learning—as a central constraint for the learning-effective implementation of FA and PASA (Xu & Brown, 2016).

To address these issues, a targeted professional development program (FORMA) was designed. Drawing on research on effective teacher professional development, key design features were identified through a review of the teacher education literature and integrated into the program (Oeksuez et al., 2024). FORMA focused on formative PASA in Grades 4–5 mathematics and was implemented as a short multimodal course consisting of three two-hour sessions over three weeks, combining face-to-face and synchronous online formats with asynchronous activities.

Building on this framework, the study examines (1) to what extent participation in the FORMA program enhances teachers’ assessment literacy regarding the design, purposes, and perceived benefits of formative PASA, and whether this effect is influenced by teachers’ epistemological beliefs; and (2) to what extent participation in the program enhances the instructional quality of formative peer- and self-assessment in teachers’ mathematics classrooms and whether this relationship is mediated by teachers’ assessment literacy.

The study employed a randomized pretest–posttest design with a wait-list control group to examine the effects of a professional development intervention on teachers’ assessment literacy and the instructional quality of PASA within FA. Participants were primary public school teachers teaching mathematics in Grades 4 and 5 in the German-speaking part of Switzerland. Depending on the research question and data availability, sample sizes ranged from 89 to 102 teachers. Following the pretest, participants were randomly assigned to a peer-assessment intervention group, a self-assessment intervention group, or a wait-list control group. Data were collected at pretest and posttest. Teachers’ assessment literacy was assessed using text-based and video-based vignettes with open-ended responses capturing declarative knowledge and situation-specific pedagogical reasoning in FA contexts. Epistemological beliefs were measured using standardized Likert-scale items. Open-ended responses were analyzed using structured qualitative content analysis. Main categories were defined deductively based on FA and PASA theory and refined inductively through data analysis. Response quality was rated on a three-point scale (1 = low, 2 = moderate, 3 = high) according to predefined criteria. Intercoder reliability was high (Cohen’s κ = .82–.90), and interrater reliability for quantitative ratings was excellent (ICC = .86–.91). All questionnaire-based measures were administered jointly within a single survey at each measurement point. To assess the instructional quality of PASA, 96 video-recorded mathematics lessons were analyzed. PASA sequences were identified by coding all lesson segments in which PASA practices occurred and served as the units of analysis. Based on prior research on FA and PASA, a literature-based rating instrument was developed deductively, with indicators refined inductively to capture enacted classroom practices. The instrument demonstrated high interrater reliability (ICC = .90–.92, 95% confidence intervals: .84–.96; all p < .001) and good internal consistency (Cronbach’s α = .86). Intervention effects on teachers’ assessment literacy were examined using repeated-measures ANOVA and ANCOVA. Group differences in the instructional quality of PASA were analyzed using one-way ANOVA with planned contrasts. Mediation analyses tested whether gains in teachers’ assessment literacy mediated the relationship between participation in the professional development program and enacted PASA quality within FA.

The intervention led to significant gains in teachers’ assessment literacy (AL), which were limited to declarative knowledge. Teachers in both intervention groups achieved significantly higher scores on the text-based vignette than those in the wait-list control group, with moderate effect sizes. In contrast, no significant improvements were observed for the video-based vignette, indicating that situation-specific assessment skills did not measurably improve. Planned contrasts showed that both intervention groups outperformed the control group, while no significant differences emerged between the peer- and self-assessment conditions. Gains in assessment literacy were positively associated with increases in constructivist epistemological beliefs. Regarding classroom practice, teachers who participated in the intervention implemented formative PASA with significantly higher instructional quality than teachers in the control group. These differences were evident across several central dimensions of PASA enactment. Mediation analyses revealed no significant indirect effects via teachers’ assessment literacy, indicating that improvements in instructional quality were not mediated by the measured knowledge gains. Overall, the findings indicate that even short-term professional development can strengthen teachers’ conceptual understanding of formative PASA and support its implementation in classroom practice, particularly when curriculum-embedded, practice-oriented materials are provided. At the same time, it remains unclear to what extent these effects are sustained over time and transferable to other subject domains, underscoring the need for longitudinal and cross-curricular research.

Andersson, C., & Palm, T. (2018). Reasons for teachers’ successful development of a formative assessment practice through professional development. Studies in Educational Evaluation, 58, 199–206. https://doi.org/10.1080/0969594X.2018.1430685 Black, P., & Wiliam, D. (2018). Classroom assessment and pedagogy. Assessment in Education: Principles, Policy & Practice, 25(6), 551–575. https://doi.org/10.1080/0969594X.2018.1441807 Buholzer, A., B, M., Zulliger von Mühlenen, S., Torchetti, L., Ruelmann, M., Häfliger, A., & Lötscher, H. (2020). Formatives Assessment im alltäglichen Mathematikunterricht von Primarlehrpersonen: Häufigkeit, Dauer und Qualität. Unterrichtswissenschaft. Advance online publication. https://doi.org/10.5281/zenodo.4305566 Cauley, K. M., & McMillan, J. H. (2010). Formative assessment techniques to support student motivation and achievement. The Clearing House: A Journal of Educational Strategies, Issues and Ideas, 83(1), 1–6. https://doi.org/10.1080/00098650903267784 Gotwals, A. W., Philhower, J., Cisterna, D., & Bennett, S. (2015). Using video to examine formative assessment practices as measures of expertise for mathematics and science teachers. International Journal of Science and Mathematics Education, 13(2), 405–423. https://doi.org/10.1007/s10763-015-9623-8 Granberg, C., Palm, T., & Palmberg, B. (2021). A case study of a formative assessment practice and the effects on students’ self-regulated learning. Studies in Educational Evaluation, 68, Article 100955. Maskos, K., Schulz, A., Oeksuez, S. S., et al. (2025). Formative assessment in mathematics education: A systematic review. ZDM Mathematics Education, 57, 679–693. https://doi.org/10.1007/s11858-025-01696-x Narciss, S., Hammer, E., Damnik, G., Kisielski, K., & Körndle, H. (2020). Promoting prospective teacher competencies for designing, implementing, evaluating, and adapting interactive formative feedback strategies. Psychology Learning & Teaching, 20(2), 261–278. https://doi.org/10.1177/1475725720971887 Oeksuez, S. S., Buholzer, A., Maskos, K., & Schulz, A. (2024). Theoriebasierte Entwicklung einer Weiterbildung zu fachspezifischem formativem Peer- und Self-Assessment. In C. Schreiner, G. Schauer, & C. Kraler (Hrsg.), Pädagogische Diagnostik und Lehrer:innenbildung: Bildungswissenschaftliche und fachdidaktische Perspektiven, 107–118. Julius Klinkhardt. Rakoczy, K., Pinger, P., Hochweber, J., Klieme, E., Schütze, B., & Besser, M. (2019). Formative assessment in mathematics: Mediated by feedback’s perceived usefulness and students’ self-efficacy. Learning and Instruction, 60, 154–165. https://doi.org/10.1016/j.learninstruc.2018.01.004 Wanner, T., & Palmer, E. (2018). Formative self- and peer assessment for improved student learning: The crucial factors of design, teacher participation and feedback. Assessment & Evaluation in Higher Education, 43(7), 1032–1047. https://doi.org/10.1080/02602938.2018.1427698 Xu, Y., & Brown, G. T. L. (2016). Teacher assessment literacy in practice: A reconceptualization. Teaching and Teacher Education, 58, 149–162. https://doi.org/10.1016/j.tate.2016.05.010 Yan, Z., Chiu, M. M., & Cheng, E. C. K. (2022). Predicting teachers’ formative assessment practices: Teacher personal and contextual factors. Teaching and Teacher Education, 114. https://doi.org/10.1016/j.tate.2022.103718