This knowledge was broadly classified into 15 components
because these were considered to be the content requirements for the
solution of the five geometry proof problems that were the focus of the
present study. Thus, the GCK as used in the present study refers to a
cluster of information that included (a) knowledge of properties of
diagrams, (b) knowledge of conventions and symbols that are associated
with such diagrams and (c) knowledge of theorems/axioms that can be
applied to specific diagrams.