This paper builds on a previous case study in which a group of lecturers from various disciplines were interviewed about their practice as facilitators of online learning. The lecturers' comments about their teaching practices revealed their awareness of specific types of teacher knowledge about online teaching. This was an unintended outcome of the previous study. Subsequently, as reported in this paper, the data were interrogated further using a new lens to investigate the extent to which these elements of teacher knowledge were evident throughout their practices. The technological, pedagogical and content knowledge (TPACK) theoretical framework enabled the researchers to identify the lecturers' views about the content taught in online and blended environments, the pedagogy which guided teaching and course design, and the technology selected to facilitate students' learning. This paper also considers practical issues about using the TPACK framework as a research tool as a lens through which to view online teachers' knowledge about pedagogy, technology and content.