Below are examples of "investigations" in Geometer's Sketchpad prepared by students in my Methods of Teaching Secondary Mathematics class over the past few semesters. An investigation is a self-guided and self-paced worksheet that leads a student to "discover" a geometric property or theorem.
All of the investigations below are PDF files. In order to view and print them, you need to have Adobe Acrobat Reader installed on your computer. If you do not already have it, click on the icon to the right to get your free copy.

Altitudes and Orthocenters of a Triangle
by Jacque Cummings

Angle Bisectors of a Triangle
by Tara Smith

Angle Relationships with 2 Parallel Lines and a Transversal
by Jeremy Hines

Angle Sums of Convex Polygons
by Dan Tothero

Finding Relationships Between Area and Parallel Lines in Triangles
by Keri Jeanes

Geometer’s Sketchpad Overview
by Erica Reilley

Investigating the Sierpinski Triangle
by Annette Busack

Law of Sines
by Brad Ingraham

Midsegment Theorem
by Erica Reilley

Parallel Lines and Angles
by Tiffany Angstadt

Parallel Lines and Transversals
by Rachael Kanusky

Pythagorean Theorem
by Justin Vallone

Sum of Interior Angles of Polygons
by Sara Otis

Triangle Congruencies
by Jesse Whitehouse