Cool Math
Coolmath: Coolmath4kids: Tessellations
Tessellations are explained and described at this website. Three basic rules are given for creating tessellations.
Geometry Help
Geometry Help: Pentagons and Hexagons
Explains the basic concept of pentagons and hexagons with step-by-step instructions and methods for solving specific problems on your own relating to this topic.
Mathigon
Mathigon: Geometry: Polygons and Polyhedra: Quadrilaterals
This lesson focuses on quadrilaterals which can fall into multiple categories based on the number of sides and the angles.
National Council of Teachers of Mathematics
The Math Forum: What Is a Tessellation?
The Math Forum defines and illustrates geometric tessellation.
Mr. Martini's Classroom
Mr. Martini's Classroom: Teacher's Figure Library: Geometric Figures
This interactive resource provides an example picture of the geometric figure chosen by students to review.
Wolfram Research
Wolfram Math World: Semiregular Tessellations
This one page Mathworld site has a number of examples of semiregular tessellations. A definition and a small amount of related information is given at the bottom of the page.
Other
Polyhedra: The Five Platonic Solids
A brief site that includes some activities to understand the figures.
National Council of Teachers of Mathematics
Nctm: Figure This: Envelopes
Explore tessellations with real world applications in this activity from the NCTM Math Challenges for Families series. Figure out what shape you would use to create a legal envelope from a single sheet of paper. Then discover how...