The increasing availability of new technologies in schools provides new possibilities
for the integration of technology in mathematics education. However, research
has shown that there is a need for new kinds of task that utilize the affordances provided by
new technology. Numerous studies have demonstrated that dynamic geometry environments
provide opportunities for students to engage in mathematical activities such as
exploration, conjecturing, explanation, and generalization. This paper presents a model for
design of tasks that promote these kinds of mathematical activity, especially tasks that
foster students to make generalizations. This model has been primarily developed to suit
the use of dynamic environments in tackling geometrical locus problems. The model was
initially constructed in the light of previous literature. This initial model was used to design
a concrete example of such a task situation which was tested in action through a case study
with two doctoral students. Findings from this case study were used to guide revision of the
initial model.