Here is another small demonstration about interactive geometry within
This demo shows the use of some planar transformations: the central
symmetry and the translation are used to build step by step part of the
mosaic. It also helps to show the relation between the composed
symmetries and the translation.
What I love is the ability within Squeak to mix, at any time, external
tools as the PaintBrush or the Etoys ones to verify some ideas or
hypothesis. This really help to improve the pedagogical efficiency of
the interactive geometry tool, which I found are, in other platform, to
much rigid in term of pedagogical exploration capabilities.
I am sorry this demonstration is in French only, but the videos are easy
to understand and figure out.