The following list contains active links to Geometer's Sketchpad (GSP) scripts. When opened in GSP, one may create the particular construction by simply starting with the given criteria named in that portion of the script. I chose these particular twenty because they are both useful and interesting.

**7a. Orthocenter, Mid-segment
triangle**

**10. Center of Nine point
circle**

**12. Triangle Centers
(H, G, C, and I)**

**14. Equilateral triangle,
given a side**

**16. Isosceles triangle, given
base and altitude**

**17. Regular Pentagon,
given a radius.**

**18. Regular Pentagon, given
a side.**

**19. Regular Hexagon, given
a side**

**20. Regular Octagon, given
a side**