Beliefs about the certainty of teaching knowledge may influence how preservice teachers engage with and learn from knowledge sources in teacher education, and their subsequent practice. In light of inconsistencies in prior findings that mainly employ epistemic questionnaires, we extended research focusing on a contextual analysis. Sixty-six elementary and lower-secondary preservice teachers in Norway responded to the Beliefs about the Certainty of Teaching Knowledge (BECK) scale in the first and second year of study, respectively. Participants believed knowledge about teaching and learning was more tentative and evolving at T2 than at T1 (t (65) = 2.0, p = 0.049, Cohen's d = 0.23). We uncovered beliefs about the ways knowledge and practice will change, reasons for change, and the rate of change in teaching knowledge. The results suggest preservice teachers hold specific beliefs about the certainty of teaching knowledge that should be addressed by teacher educators.