Strong subject matter knowledge has been highlighted
over the years to be a critical element of a mathematics
teacher’s knowledge base. This study was motivated
primarily by research conducted in the area of preservice
teacher knowledge which has uncovered serious
deficiencies in their conceptual understanding. The
research was narrowed by the lack of research
previously conducted in the area of trigonometry. The
van Hiele model of development of geometric thought
(van Hiele, 1984) was adapted to be specific to
trigonometry for this research and was validated by the
use of APOS theory (Dubinsky & McDonald, 2002). An
assessment tool was formulated based upon this model
and thus far has been pilot tested amongst 19 preservice
teachers.