Cuemath
Cuemath: Angle Sum Theorem
Explore the world of the angle sum theorem in this mini-lesson. Provides a definition and solved examples that help with understanding their properties. Includes practice questions with answers.
National Council of Teachers of Mathematics
Nctm: Illuminations: Shape Sorter
Students learn how to categorize plane figure polygons using Venn Diagrams with this computer based tool.
Cuemath
Cuemath: Plane Shapes
A comprehensive guide for learning all about plane shapes with definitions, properties, types, solved examples, and practice questions.
University of Regina (Canada)
University of Regina: Math Central: Lesson: Mr. Z's 5 Minute Game of Geometric Pandemonium
Students make a series of geometric drawings of points, obtuse angles, rays, polygons, and the like. Each child is given one but not allowed to show anyone else. The drawing is then taped to the back of the child in front of them. The...
Other
Ic Teachers: Shapes Quadrilaterals
Are you looking for a very basic website that will explain the basic properties of a quadrilateral? Use this site to learn about the properties of a square, rhombus, rectangle, parallelogram, trapezoid, and kite. There are also some...
NumberNut
Number Nut: Shapes, Symbols, and Colors: 2 D Shapes
Did you know that two-dimensional shapes are also called polygons? This lesson describes the various 2-D shapes and includes two interactive games to reinforce skills.
National Council of Teachers of Mathematics
Nctm: Illuminations: Cutting Corners
Students will use their knowledge of plane figure attributes to create and view shapes by cutting and rotating shapes to stimulate discussions on names and attributes of various shapes they do not regularly encounter.
BBC
Bbc: Bitesize: Maths: 2 D Shapes
Learn about the properties of 2-D shapes: circles, triangles, polygons, and quadrilaterals. Includes information, video, and examples about each, with games and quizzes for reinforcement.
Texas Instruments
Texas Instruments: What's the Angle?
Students discover properties of interior and exterior angles of convex polygons using the TI-89 and Geometer's Sketchpad.
Wolfram Research
Wolfram Math World: Acute Triangle
This MathWorld site gives a short discussion on acute triangles with links to related terms and topics. The site offers a discussion on the least number of acute triangles to compose various polygons, and a discussion on the relationship...
Shodor Education Foundation
Shodor Interactivate: Lesson: Geometry in Tessellations
This upper elementary and middle school lesson plan explores tessellations and their geometric properties. Plenty of interactive support is available for students. Lots of resources for teachers to use.
Other
Antonio Gutierrez: Geometry From the Land of the Incas
Discovering the properties of constructions, seeing proofs in action, and viewing problems come to life here with this wonderful use of technology in the classroom. Single steps are explained and illustrated one at a time so that the...
Illustrative Mathematics
Illustrative Mathematics: G C Right Triangles Inscribed in Circles I
This task provides a good opportunity to use isosceles triangles and their properties to show an interesting and important result about triangles inscribed in a circle with one side of the triangle a diameter. The fact that these...
Texas Instruments
Texas Instruments: Triangle Inequalities
This activity will help students visualize the properties of triangles stated in the theorems. By dragging the vertices, the students can see that the properties hold regardless of the size of the triangles and which sides are the...
Writing Fix
Writing Fix: Shape "Monsters" at Night
Using Melanie Watt's book entitled Scaredy Squirrel at Night, this multi-day lesson allows students to apply information about Scaredy Squirrel's night time experiences and its fears as their final product model. Students will create...
Los Angeles County Office of Education
Los Angeles County Office of Education: Quadrilateral Quest
Use your knowledge of properties of quadrilaterals to correctly match quadrilaterals.
CK-12 Foundation
Ck 12: Geometry: Equilateral Triangles
[Free Registration/Login may be required to access all resource tools.] In this lesson students apply the properties of equilateral triangles. Students examine guided notes, review guided practice, watch instructional videos and attempt...
CK-12 Foundation
Ck 12: Geometry: Equilateral Triangles
[Free Registration/Login may be required to access all resource tools.] This concept will teach students the properties of equilateral triangles and how to apply them to solve problems. Students examine guided notes, review guided...
CK-12 Foundation
Ck 12: Geometry: Parallelograms
[Free Registration/Login may be required to access all resource tools.] This concept teaches students properties of and theorems about parallelograms and how to apply them.
Khan Academy
Khan Academy: Identifying Quadrilaterals
Learn about the properties of rectangles, rhombuses, and squares, and practice identifying them. Includes hints for questions. CCSS.Math.Content.3.G.A.1 Understand that shapes in different categories
CK-12 Foundation
Ck 12: Geometry: Quadrilaterals That Are Parallelograms
[Free Registration/Login may be required to access all resource tools.] This concept teaches students how to prove that a quadrilateral is a parallelogram given the properties of parallelograms.
Alabama Learning Exchange
Alex: What Do We Have in Common?
This inquiry lesson explores the definitions of quadrilaterals and the properties of the diagonals of quadrilaterals to classify quadrilaterals. Students will work cooperatively to justify conclusions. This lesson plan was created by...
Cuemath
Cuemath: Congruent Triangles
Explore the world of congruent triangles in this mini-lesson. Provides a definition and examples that help with understanding their properties. Includes a short video and practice questions with answers.
Math Open Reference
Math Open Reference: Decagon (10 Gon)
Learn about decagons with this resource which offers detailed explanations, examples, and an interactive. Subjects covered include properties of decagons. Links to related topics.