The current study examined the time spent in various types of science instruction with regard to teachers' awareness of instructional activities. The perceived effectiveness of instructional activities in relation to the allocation of time was also examined. A total of 30 4th grade teachers (17 female, 13 male), from seven different primary schools, participated in the study. First, the teachers completed a questionnaire regarding student-centred and teacher-centred activities and their effectiveness. Subsequently, classrooms were videotaped during a 40- minute science lesson. The videos were coded for the type and duration of instruction and analysed. During science lessons, teachers misidentified almost half of the activities in the questionnaire as being student-centred, and rated these activities as more effective. Based on classroom observations, the teachers were found to primarily use teacher-centred instruction. Based on the classroom videos, it was found that teachers who were more aware of student-centred activities spent less time on teacher-centred activities. Additionally, teachers who found teacher-centred activities more effective tended to spend more time on teacher-centred activities and thus less time on student-centred activities and orientation.