This mixed-method study explored 54 Finnish Grade 1 teachers' professional vision and teaching experience. Teachers' retrospective think-aloud interviews, conducted while watching their eye-tracking recordings of classroom actions, were analysed according to the domains of knowledge-based reasoning. Negative associations between teaching experience and amount of knowledge-based reasoning were found. The qualitative examination of three teachers with different amounts of teaching experience provided concrete examples and broadened the findings. We suggest that teachers’ knowledge-based reasoning should be seen not only as an ability that increases with experience but also as an ability that can be trained in early career stage.