Geometry

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3-D Geometry & Polyhedra

Math Forum's Studying Polyhedra
Interactive: Study the Platonic solids.
Paper Models of Polyhedra
80+ nets of polyhedral models.
MatHSoliD Java Applet (Interactive)
All Platonic and Archimedean Solids.
NCTM's Illuminations (Interactive)
Geometric Solids and Their Properties: Grades 3-5.
NCTM's Illuminations (Interactive)
Cubes and Isometric Drawings: Students
NCTM's Illuminations (Interactive)
Cubes and Isometric Drawings: Teachers
The Geometry Junkyard: Unfolded Polyhedra
Links
Pedagoguery Software Inc. (Interactive)
Free trial downloads
Math Cats: Geometric Space Forms
Create polyhedral nets with compass and straightedge
Straw Polyhedra
Soda staws & string.
Virtual Polyhedra - An Encyclopedia of Polyhedra
Thousands of virtual reality polyhedra to explore.
University of Utah
Interactive Platonic Solids via Java applet.

Constructions

Kocmoud's Constructions WIMS Ruler & Compass Constructions MathsNet Interactive Constructions
Grand Valley State: Geometric Constructions

Geometry of Nature

Book: The Geometry of Nature Pictures: The Geometry of Nature

M.C. Escher

MCEscher.com
Escher's official Website.
The Oldest Escher Collection of the Web
Works by Escher & artists inspired by him.
MC Escher - Artist or Mathematician ?
Biographical detail and tutorial.

Similar Polygons

Pink Monkey Notes - Similar Polygons

Tessellations

Math Formum Tessellation Tutorial
Definitions, samples, interactive tessellation engine.
Tantalizing Tessellations
Ten complete tessellation lessons.
David Annal's Tessellations.org
History, gallery, do-it-yourself.
Science U's Introduction to Tilings and Tessellations
Examples and 2 interactive tessellation engines.
Cool Math's Tessellation Page
Definitions and examples.

Transformational Geometry & Symmetry

MathsNet Transformational Geometry Unit
Interactive unit: four levels of instruction.

Leslie Howe's Transformation Unit
Simple interactive unit.
NCTM: Congruence, Similarity, and Symmetry
Visualizing transformations: interactive applets.
UGA's Transformational Geometry Unit
Ten day unit for Geometer's SketchPad.
Java Gallery of Interactive Geometry Gallery of Interactive Geometry

Pick's Theorem

Cut The Knot (Interactive)
Applet to demonstrate Pick's Theorem.
IES Manipula Math Java Applets
279 math applets. 91 in middle school geometry

Geometer's Sketchpad Resources

How to Choose a Real-World Problem
The purpose of this list is to help you choose real-world problems that you can investigate on your own with Geometerís Sketchpad.
Geometry Learning Units
This site provides a variety of geometry lessons that use real-world problem scenarios.
How Now Pythagoras?
This site provides a fun activity using the Pythagorean theorem for students interested in woodworking.
Determining Altitude of Iridium Flares
This site provides an activity for students interested in space exploration. Note this activity is more advanced.
The Goal Angle Problem
This site provides a fun activity exploring angles for students interested in soccer.
Geometry Through Art
This site uses art as a means for learning geometerís sketchpad.
Lesson Plans Using GSP
This site provides objectives and lesson plans for grades 6-8. These lessons are for use with the Geometerís Sketchpad.
Lesson Plans for the Geometerís Sketchpad
This site provides 17 lesson plans that use the Geometerís Sketchpad.
GSP Lessons
This site provides 13 lesson plans written for use with the Geometerís Sketchpad.
The Geometerís Sketchpad Equations of Circles
This site provides a GSP lesson plan for generating the equation of circles.
The Geometerís Sketchpad Introductory Lab
This site provides a GSP introductory lesson plan.
The Geometerís Sketchpad Modeling a Ferris Wheel
This site provides a fun activity for students to learn the GSP animation feature by modeling a ferris wheel.
101 Project Ideas for Geometerís Sketchpad
This site provides information for ordering a book from the maker of Geometer's Sketchpad titled "101 Project Ideas for Geometer's Sketchpad." There are also 15 projects available for download directly from this site.