It is difficult to transform research evidence into teacher practice; indeed it has been argued that educational research is not very useful to teachers. In this paper, we explore teacher knowledge about a relatively new area of research concerning the role morphemes play in spelling, and seek to transform their practice. We find that although reference to morphology is beginning to be made in English policy documents, teachers make limited use of morphology in their practice. After attending a course on the role of morphemes in spelling, teachers' own awareness of morphology increased and this was reflected in their practice. This in turn caused their pupils to make significant gains in spelling, compared to a control group. This reinforces the proposition that explicit instruction about morphemes is helpful to children's learning. It demonstrates the fact that research can be transformed into teacher practice, but it also illustrates the difficulties. Policy documentation alone is insufficient. Professional development can effect change but this may be hard to sustain. Children's gains are contingent on teachers continuing to dedicate class time to focused intervention.