Educational computing has much to offer mathematics education, particu
larly when software is designed which provides students with the oppor
tunity to go beyond practicing basic skills and solving routine proble
ms, and instead supports mathematical discovery and exploration. Altho
ugh drill and practice is still the category of software employed most
frequently by mathematics and science teachers who use computers [1],
software which functions as a cognitive tool for exploration and sens
e-making is becoming more evident in both classroom and research envir
onments [2, 3]. The purpose of this article is to report on the result
s of a research study involving an exploratory learning environment, o
r mathematical microworld, for transformation geometry. The goal is to
outline the principles underlying the design of the environment as we
ll as to present an analysis of the learning of a group of middle scho
ol students who interacted with the microworld over a period of severa
l weeks.