Students in 4 Canadian high school physics classes completed instructional sequences in two key physics topics related to motion--Straight Line Motion and Newton's First Law. Different sequences of laboratory investigation, teacher explanation (lecture) and the use of computer-based scientific visualizations (animations and simulations) were experienced by different groups of students. Tests based on the Force Concept Inventory were used to measure their understanding of the key concepts. Student results were also analysed in terms of academic achievement level and sex and a retention test was conducted 12 weeks after instruction. Teaching sequence was found to significantly influence students' conceptual development. Introducing the topic with a laboratory or visualization activity is more effective for concept learning. Lecture first followed by laboratory and visualization activities (in either order) was the least effective approach. On the first sequence the highest achieving students achieved statistically greater learning gains. Students' sex did not yield statistically significant differences. For the second sequence, female students in the laboratory-first sequence achieved significantly better than any other group. While effects reported are small, this study provides an initial analysis of the importance of teaching sequence when adding scientific visualizations to the physics teaching repertoire. (Contains 7 tables and 2 figures.)