The larger study of which this paper is part resembled
a study of exemplary practice (Fraser and Tobin, 1989). I
invited the teacher to participate because I knew from his
professional development activities for other teachers that he
was active in using graphics calculators in his teaching; and
knew that many of his past students had achieved outstanding
results in tertiary entrance examinations. The study was non-
interventionary in that I did not provide or suggest activities.