This paper attempts to establish a conceptual basis on which beginning teachers may be introduced to investigative science teaching in a way that accommodates the teacher voice. It draws mainly on preliminary theory from the shared reflections of 20 science teachers, augmented by a more general interview-based study of the experience of early professional learning of 18 new teachers. Internationally, it is situated in the wider concern in the literature with the nature of science, mainly in initial teacher education. Empirically located within the Scottish context, a grounded epistemological base of teacher knowledge is illustrated and presented as components of confidence in a cycle of professional learning that needs to be set in motion during initial teacher education. It is proposed that, given protected experience in their early attempts to teach investigatively, new teachers can begin to develop a confident pedagogy of loose opportunism that comes close to authentic science for the children they teach.