Making implicit practice explicit: How do upper secondary teachers describe their reading comprehension strategies instruction?

•In the written form, teacher practices were made more explicit than in interviews.•Teachers combined multiple reading comprehension strategies in each instruction.•Subjects seemed to matter more than strategies in the teachers’ instruction.•Activating tacit knowledge offered valuable teacher professional development.•A short professional development course showed teacher learning over time.

This study examined the activation of teachers’ tacit knowledge of reading comprehension strategy instruction as part of a teacher professional development course. Although studies have examined professional development courses that inform teachers about research-based knowledge, there has not been much research on courses activating teachers’ tacit knowledge, as is the case with the present study. This qualitative study analyzed 21 upper secondary teachers’ instructional design; which strategies they promoted, how these differed across subjects, how their instruction was made explicit through professional development, and how the course contributed to the activation of tacit knowledge. This study demonstrated teacher learning over time, where implicit practices were made explicit through written narratives and increased metacognitive awareness.