This article investigates the influences on a teacher's uncertainty through the use of storyline methodology. As a research method, storylines can be utilised to educe a teacher's responses to inquiries into their practice. The particular storylines in this article are drawn from the uncertainty work of Floden and Clark (1988) and reflect aspects of teaching that are of concern to all teachers: content knowledge, assessment, teaching and learning and knowledge. By drawing these storylines together, we present two key findings to our research question: "how does a teacher accept uncertainties in his teaching," and "how does that acceptance interact with his implementation of a new course?" Our analysis suggests that a teacher's continued professional learning is underpinned by an acceptance of uncertainty in their teaching. Further, the analysis highlights the value of a culture of long-term professional learning that allows teachers to respond positively to uncertainties that are important to them. This suggests that a science department that is committed to questioning practice may provide many of the supports that teachers need to pursue their own questioning of practice.