Analysis and Results
Table 3 contrasts the potential and actual student responses to the task. The task has
the potential for exploration of unfamiliar mathematical ideas; the perimeter was given and
working backwards was required to find the dimensions. As only one of three unknowns
was given, substitution and algebraic manipulation would not provide a numerical solution.
The existence of more than one rectangle with a perimeter of 38cm provided an ‘unusual
twist’. Some examples of the potential discovered complexities include (a) How does the
pattern L + W = 19 relate to the perimeter formula or the context? (b) Why are the values
of L and W restricted? (c) What mathematical arguments explain what happens? The
conceptual ideas accessed may commence with generalisations or with tabulation of
specific examples to find a pattern and then explain why it exists. These complexities
involve student connection of solution pathways using various representations (specific
numerical examples, tables of numbers, numerical patterns, algebraic patterns, algebraic
variation to provide a general argument). Different assumptions are possible (number of
decimal places) and elegant solutions may result (argument through variation using algebra).