Brain Teasers: Geometry Puzzles
- Slice and complete various figures to form requested shapes.
- http://brainden.com/geometry-puzzles.htm

Spaghetti and Meatballs For All
- Webquest for 3rd-8th graders comparing the perimeter and area of rectangles. Relates to the book "Spaghetti and Meatballs For All!" by Marilyn Burns.
- http://www.viterbo.edu/academic/ug/education/edu250/kljohnson/

Cynthia Lanius' Lessons: Geometry Online
- Have fun learning through activities about polygons, triangles, circles, and the volume of cylinders. Page includes an historic timeline, SAT type quiz, and glossary of terms.
- http://math.rice.edu/~lanius/Geom/

Teen Math Whizzes Go Euclid One Better
- Features a discussion about the works of two teenagers, David Goldenheim and Daniel Litchfieldm, from Connecticut. They helped find a solution that eluded Euclid in finding a method to partition a line into any number of equal sections.
- http://jwilson.coe.uga.edu/Texts.Folder/GLaD/GLaD.Comments.html

Tim's Triangular Page
- Learn about the basic properties, formulas, theorems and different types of triangles. Includes proofs and illustrations.
- http://sakharov.net/triangle.html

Geometry
- Explains and describes geometric terms, measurement of angles, types of figures, coordinate graphs, areas and volumes.
- http://www.mathleague.com/help/geometry/geometry.htm

Tangrams
- Choose a puzzle, then click and drag virtual tangram pieces to solve it. From PBS.
- http://pbskids.org/sagwa/games/tangrams/index.html

Point Out the View
- Use visualization to determine how four different people see a set of 3-D blocks. From PBS Kids.
- http://pbskids.org/cyberchase/games/pointofview/pointofview.html

Spaceship Builder
- Use a virtual geoboard to help Dr. Marbles design a new fleet of cyberspace ships. From PBS Kids.
- http://pbskids.org/cyberchase/games/perimeterarea/perimeterarea.html

Figures and Polygons
- Shows different types of straight-sided shapes with up to ten sides. Gives the total number of degrees for each side.
- http://www.mathleague.com/help/geometry/polygons.htm

Areas, Volumes, Surface Areas
- Use these simple illustrated formulas to calculate volume and surface area of various shapes.
- http://math2.org/math/geometry/areasvols.htm

Fugues of the Well-Tempered Clavier
- Interactive Director movie comparing a fugue by Johann Sebastian Bach to a Möbius strip.
- http://jan.ucc.nau.edu/~tas3/wtc/i10.html

The Pythagorean Theorem Lesson
- A lesson on the pythagorean theorem with the objective that the you will discover for yourself the actual theorem.
- http://www.arcytech.org/java/pythagoras/index.html

Geometria
- A program for computing lines, surfaces and volumes of the main plane and solid figures, through direct and indirect formulas. Includes multiple languages.
- http://www.elvenkids.com/tools/geometria/Geometria.php

Introduction to the Works of Euclid
- Covers the life of Euclid and a discussion of Euclidean geometry.
- http://www.obkb.com/dcljr/euclid.html