Curated OER
Interior Angles of Regular Polygons
Students investigate the interior angles of a triangle. In this geometry instructional activity, students create the formula to calculate the angles inside a triangle. They observe the total sum of a triangles angle on the navigator.
Curated OER
Congruent Triangles
Students identify properties of triangles. In this geometry lesson, students differentiate between similar and congruent triangles. They use the umber of sides to help define the angle of the polygon.
Curated OER
Exploring Geometry and Algebra using Cabri Jr. Application.
Learners solve geometric problems with algebra and graphing in this lesson. They will prove the bisectors theorem using the Cabri Jr. application, which requires Cabri on their TI.
Curated OER
Angles of a Triangle
Learners explore the measures of the angles of a triangle in this geometry lesson. They use Cabri Jr. to investigate the sum of the measures of the interior angles of a triangle, and examine the relationships between the interior and...
Curated OER
Measuring Angles in a Triangle
High schoolers investigate the sum of the measures of the angles of a triangle. They draw a triangle and measure the interior angles. Using Cabri Jr., learners find the sum of the measures of the interior angles. The instructional...
Curated OER
Triangle Inequality Theorem
High schoolers investigate the relationship between angle measures and sides of a triangle and the relationships among the three sides of a triangle. The use of technology (Cabri, Jr.) allows learners to make and test conjectures as they...
Curated OER
Shortest Distance Between Points and Lines
Learners use technology to determine the shortest between two points in a plane. They are required to support their analytic explanations with visual illustrations.
Curated OER
Cabri Jr. - Getting Started with Triangles
Young scholars explore a basic triangle construction. In this beginning geometry lesson, students investigate the steps to necessary to create an equilateral triangle with Cabri Jr.;
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Faq About Proofs
This site provides links to questions sent in to Dr. Math about proofs. Topics covered include what proofs are, how to understand them, and how to build them, and much more. Be sure to click on the links which you believe may be helpful.
Maths Challenge
Maths challenge.net: Perpendicular Construction
This is a "three star" geometry problem where prior math problem skills and proof experience is recommended to solve this "Perpendicular Construction" problem.
Maths Challenge
Maths challenge.net: Tick Tock Triangle
This is a "three star" geometry problem where prior knowledge of probability is required to solve this "Tick Tock Triangle" problem, have fun!
Maths Challenge
Maths challenge.net: Leaning Ladders
Use your right triangle solving skills to solve this ladders in a hole problem.
Maths Challenge
Maths challenge.net: Right Triangle Equal Parts
A geometry proof problem involving a right triangle and finding angles of equal measure.
Maths Challenge
Maths challenge.net: Triangle Area
Find the area of this triangle in a coordinate plane.
Maths Challenge
Maths challenge.net: Equal Angles
A geometric proof. Prove two angles in this model are equal in measure.
Maths Challenge
Maths challenge.net: Triangle in a Square
A "three star" geometry problem requiring some prior knowledge in math and proofs to maximize the area of an inscribed triangle in terms of the hypotenuse.
Maths Challenge
Maths challenge.net: Inscribed Rectangle
This is a proof problem, considered a "three star" geometry problem requiring knowledge of proofs and properties of circles to solve this equal area of inscribed polygons problem.
Maths Challenge
Maths challenge.net: Three Circles
This is a proof problem, considered a "three star" geometry problem requiring knowledge of proofs and properties of circles.
Maths Challenge
Maths challenge.net: Measuring Mountains
Use your triangle solving skills to solve this triangle problem and then apply it to the real world.
Maths Challenge
Maths challenge.net: Maximum Square
A challenging proof like geometry of finding the square inscribed in a triangle.
Maths Challenge
Maths challenge.net: Isosceles Trapezium
This is a "three star" geometry problem where prior knowledge of problem solving and thinking through proofs is recommended to solve this trapezoid inscribed in a semicircle problem.
Maths Challenge
Maths challenge.net: Right Angle Reasoning
A geometry problem for students to use their mathematical reasoning skills to explain a right triangle property.
Texas Education Agency
Texas Gateway: Using Logical Reasoning to Prove Conjectures About Quadrilaterals
Given conjectures about quadrilaterals, the student will use deductive reasoning and counter examples to prove or disprove the conjectures.
Oswego City School District
Regents Exam Prep Center: Triangle Inequality Theorems
This tutorial discusses triangle inequality and provides practice problems for students to try out their skills. The teacher resource page contains a lesson plan for a yummy activity involving licorice.