The purpose of this study was to investigate the effects of increased explicitness ofassessment criteria on students’ performance and motivation. Successive levels ofexplicitness, from feedback based on (implicit) criteria to a combination of exemplarsand explicit criteria, were implemented in eight classes at four schools (n = 153 students,12–13 years old) during four teaching sequences in science. Data was collected on: (a)student performance through knowledge tests, (b) student motivation (self-efficacy, goalorientations, and self-regulation) through questionnaires, and (c) perceived clarity of goalsand criteria through “exit tickets.” Findings show that student performance improvedfrom pre-, to post-tests at all schools (effect sizes from 0.82 to 1.38), but not in relationto the level of explicitness. There was also an increase in self-efficacy for low-performingstudents, but, again, not in relation to explicitness. These changes are instead assumedto be an effect of the formative feedback provided as part of the intervention. The onlychange related to the level of explicitness, was an increase in self-regulation scores byhigh-performing students when having access to both exemplars and explicit criteria.Findings therefore suggest that low to medium levels of explicitness in assessment haveno discernable effects on students’ performance or motivation.