We report the results of a classroom study of three secondary mathematics
teachers who had no prior experience teaching with technology as they began to use an
online mathematics learning system in their lessons. We gave the teachers only basic
instruction on how to operate the system and then observed them intensively over four
school terms as they taught using it. We documented changes in the teachers’ Pedagogical
Technology Knowledge and subsequently classified their various roles as technology
bystanders, adopters, adaptors and innovators. Results show that all teachers made some
progress toward using the system in more sophisticated ways, but the improvements were
not uniform across the teachers. We suggest possible reasons to explain the variation and
discuss some implications for teacher professional development.