Teachers' conceptions of teaching, and broad approaches to teaching reported by teachers are both commonly found to range from teaching as information transmission, through to teaching as supporting students' own knowledge constructions. Further, conceptions and approaches have been found to correlate, suggesting that there might be some functional relationship between conceptions and actual teaching practices. But in teacher conception research, participants are commonly asked in interview to reflect on teaching generally, and not to report on particular teaching episodes. The conceptions reported might thus actually be "post hoc" reflections on past experience, and not indications of detailed functional decision steps. In work reported here, teachers described their reasoning when planning recent teaching episodes. Were higher level conceptions of teaching directly involved in these teachers' detailed planning, then some vestige of that might be expected to manifest. While student-centredness varied, teacher thinking during actual planning seemed more about contextually localised models of what students might do, than about evoking general conceptions of teaching. The constraints that this finding places on the interpretation of conceptions of teaching, and possible implications for teacher development, are discussed.