Pedagogical content knowledge (PCK) is a foundation for teacher standards such as the Interstate Teacher Assessment and Support Consortium (InTASC) (Council of Chief State School Officers, 2011) and a critical element of teacher preparation and professional development for multiple fields, including science teaching (Purzer, Moore, Baker, & Berland, 2014). But several years ago Settlage (2013) presented a powerful critique of PCK, rejecting the way it positions knowledge in the abstract, "solely … what teachers store in their heads" (p. 10) and calling for more evidence connecting PCK conceptualisations to actual teaching activity. In truth, theoretical descriptions of PCK abound (Darling-Hammond & Bransford, 2005; Hashweh, 2005; Lee & Luft, 2008) and most utilise the lens of the researcher (Lee & Luft, 2008). While this helps us conceptualise teaching and imagine what could be, what is needed are more illustrations of what is.Abell (2008) asked if PCK is still a viable framework for teaching and educational research, and our conversations with colleagues raised similar concerns, especially when attempting to bridge the theory-to-practice gap and describe how PCK could be utilised as a framework for improving classroom teaching practice. A robust body of research positions reflective inquiry as the foundation for adaptive teaching practices (Author, 2013;Korthagen & Vasalos, 2005;Loughran, 2010;Rodgers & Raider-Roth, 2006) and during reflection pedagogical knowledge and content knowledge elements of PCK can be combined with observations of students' responses, resulting in renewed and revised instructional actions. Such reflective, adaptive inquiry utilises the integrative knowledge that is PCK (Gess-Newsome, 1999) and the resulting instructional actions enact PCK: they put into action the amalgamation of content and pedagogical knowledge (Shulman, 1987) with "particular inner knowledge" (Borowski, et al., 2012, p. 25) unique to the teacher, the context, and the students at hand. Our

This research explored the practices of one science teacher, expert in her field, as she worked to enact science discourse that incorporated language in naturalistic and rigorous ways. Difficulties in mastering the language of science contribute to troubling and persistent achievement gaps across demographic and gender groups. Science learning is based in discourse, with knowledge built by asking questions, exploring, revising views and asking new questions. But all too often students are not able to participate fully in these opportunities for discourse that is engaging and exploration due to the difficulty of science language. Qualitative analysis of this teacher's use of science discourse to establish clear links between essential science language and concepts and pre/post analysis of a science language assessment reveal important ways that teachers and researchers can work together to design and deliver instruction and assessment that supports students' mastery of sophisticated language and concepts. Results have implications for theory regarding science discourse; language learning, and conceptual development; and provide a model for teacher-researcher partnerships exploring important problems of teaching practice.