This activity gives you instructions using a geometer's sketchpad file entitled "Points of Concurrency". With the sketchpad files students will learn the special properties of the circumcenter, incenter, centroid, and orthocenter when they are contructed in a triangle. With sketchpad it is possible to change the type of triangle and notice how the four points change.
The zipped file contains a copy of the lesson and the sketchpad file. You will need to own geometer's sketchpad to use the file.