Texas Instruments
Texas Instruments: Triangulation Problem
In this Computer Algebra System (CAS) activity, students use 'landscape' paper and fold the top left corner of the page so that it just touches the bottom of the page. They calculate the area of the triangle formed by the bottom left...
Texas Instruments
Texas Instruments: Exterior Angle Theorem
This activity uses the graphing calculator to show the relationship between an exterior angle of a triangle and the two remote interior angles.
Texas Instruments
Texas Instruments: Angles of a Triangle
In this activity, students will measure angles and investigate the relationships between interior and exterior angles of a triangle. They understand the definition of interior angles, exterior angles, adjacent angles, supplementary...
Texas Instruments
Texas Instruments: Collecting Data in Geometry
This activity is designed for students to make conjectures about triangles. Students will create three lists to represent the measures of the angles of the triangle. The entire class list will then be sent to each student for analysis,...
Texas Instruments
Texas Instruments: Sum of Interior Angles in a Triangle With Cabri Jr.
Students will discover the sum of the interior angles in a triangle using the Cabri Jr. Application.
Texas Instruments
Texas Instruments: Cabri Jr. Side Splitter Theorem
Cabri Jr. activity to study the Side-Splitter Theorem. Page numbers come from Prentice Hall Geometry textbook.
Texas Instruments
Texas Instruments: Measuring Polygons an Introduction to Cabri Jr.
This activity is designed as an introduction to using the Carbri Jr. application on the TI-83+/84+ calculators. Students are guided through the menu system and are shown how to draw triangles, quadrilaterals and and a pentagon. Perimeter...
Texas Instruments
Texas Instruments: Area of Triangle
This Cabri Geometry activity enables students to review the relationship between the height of a triangle and its perimeter and area.
Primary Resources
Primary Resources: 2 D and 3 D Shapes
Here is a huge collection of teacher resources for teaching 2-D and 3-D shapes. Includes smartboard and PowerPoint presentations, as well as worksheets and helpful hints.
Beacon Learning Center
Beacon Learning Center: Congruent or Not?
Students explore congruent polygons in this interactive web lesson.
The Math League
The Math League: Figures and Polygons
This site provides definitions of different types of polygons and figures.
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Rectas Notables De Un Triangulo
In Spanish. Interactive activities dealing with the concept of angle bisector, median and altitude of a triangle. A description of the circumcenter and centroid are given along with a visual representation. [Requires Java.]
CK-12 Foundation
Ck 12: Elem Math: Counting Rectangle,s Squares, Circles, and Triangles in Sets
[Free Registration/Login may be required to access all resource tools.] The video displays a set of figures and reviews triangles by number of sides. Then all of the triangles out of the set of figures are chosen. The video is followed...
CK-12 Foundation
Ck 12: Elem Math: Counting the Number of Different 2 D Shapes in a Set of Figures
[Free Registration/Login may be required to access all resource tools.] The video defines a triangle by the number of sides and then determines which of the figures in the diagram are triangles. The video is followed by additional...
![Pbs Mathline Lesson Plan: Mirror, Mirror [Pdf] Lesson Plan](https://static.lp.lexp.cloud/images/attachment_defaults/resource/large/FPO-knovation.png "Pbs Mathline Lesson Plan: Mirror, Mirror [Pdf] Lesson Plan")
PBS
Pbs Mathline Lesson Plan: Mirror, Mirror [Pdf]
The goal of this PBS lesson is for students to apply spatial reasoning, problem solving, and critical thinking skills to assess which regular polygons will tessellate. A detailed lesson plan that includes related worksheets, lesson...
PBS
Pbs: Mathline: Tessellations Wow! [Pdf]
An integrated geometry lesson on spatial sense in which students identify and use different shapes to create a tessellation. "Through a variety of modalities such as writing, music, art, poetry, and literature, students are introduced to...
SEDL
The Timss Mathematics Segment: Geometry
This site explores the area of congruent triangles and how it is a difficult area to understand.
Curated OER
Nova Scotia Dept. Of Education: Mathematics 8: Geometry Diagrams
A collection of diagrams that complement Mathematics 8, a Grade 8 Math text, have been posted here. The diagrams were created using The Geometer's Sketchpad,
Texas Instruments
Texas Instruments: Cabri Jr. Getting Started With Triangles
This activity was developed as an introduction to the Cabri Jr. application on the TI-84 calculator. It investigates some basic properties of triangles. [Requires Adobe Reader.]
Texas Instruments
Texas Instruments: Walking the Fence Line, Then the Hypotenuse
In this activity, students use the Geoboard to determine the length of the hypotenuse of a right triangles. [Requires Adobe Reader.]
Texas Instruments
Texas Instruments: The Simson Line
Students study the Simson line and analyze the relationship it shares with its triangle. [Requires Adobe Reader.]
Texas Instruments
Texas Instruments: Math Today Dangerous Births
In this activity, using the USA TODAY Snapshot "Dangerous births" students will explore the geometric relationships of triangles using perpendicular bisectors of the sides, bisectors of the angles and medians of the triangle. They will...
Texas Instruments
Texas Instruments: Try Angle?
In this activity, students investigate properties of triangles by randomly generating possible side lengths for triangles. They learn to determine if three line segments can form a triangle. They also learn to classify triangles as...
Texas Instruments
Texas Instruments: Investigating Special Trangles
This activity will help students visualize the construction of these special triangles and find the ratios of the sides. It will help students later when they being trigonometry. [Requires Adobe Reader.]