The following links to an updated eexample containing the two activities from the original applets.
The applet use interactive geoboards to help students identify simple geometric shapes, describe their properties, and develop spatial sense. helping students reach the goals described in the Geometry Standard.

Investigating
Geometry Concepts on GeoBoards (4.2)
This twopart eexample presents a virtual 11x11
pin grid and triangular grid where students can explore geometric shapes and
measurements with the option of shading
areas, hiding pegs, deleting segments, and moving vertices.

This twopart example below contain the original applets, which conform more closely to the pointers in the book.

Making Triangles (4.2.1) Focuses attention on the concept of triangle, helping students
understand the mathematical meaning of a triangle and the idea of
congruence, or sameness, in geometry. 

Creating Polygons (4.2.2) Students make and compare a variety of polygons, describing the salient properties of the shapes they create. 