Effects of reflection phase timing on pre-service mathematics teachers’ diagnostic processes

Empirical research has underlined difficulties regarding knowledge about proof for learners of all ages. As knowledge about proof can indicate an individual’s

understanding of proof, it is thus mandatory to find means to support students

effectively. In an intervention study with 61 9th grade students, we examined to what extent it is possible to foster students’ understanding of proof by explicitly addressing knowledge about proof principles. The intervention covered five lessons integrated in regular mathematics classes distributed over a half school year. The positive effect suggests that the intervention could foster students’ knowledge about proof principles using only a short amount of time. However, the results also raise questions regarding the explicit formulation of rules and criteria for mathematical proof.