Oswego City School District
Regents Exam Prep Center: Writing a Proof: Direct Euclidean Proofs
This site is a look into the world of geometric proofs. You'll learn what a proof is and about the different types of proofs. Try the practice page to check your understanding. Teachers can check out the teacher resources for lesson and...
Texas Education Agency
Texas Gateway: Constructing and Justifying Statements About Geometric Figures
Students will distinguish between undefined terms, definitions, postulates, conjectures, and theorems and investigate patterns to make conjectures about geometric relationships.
OER Commons
Oer Commons: Mars: Proving the Pythagorean Theorem
This lesson is intended to help you assess how well learners are able to produce and evaluate geometrical proofs. PowerPoint slides are included with the lesson.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Building Two Column Proofs
Use this site to find details of how to construct a two column proof. Dr. Math responds to a question posed by a student and details the reasons for the order of steps and shows two different ways to do the same proof.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Order of a Proof
The site gives a diagram of steps to a proof. Dr. Math explains why the step order of a proof is important.
Science Education Resource Center at Carleton College
Serc: Pythagorean Theorem Investigations
In this activity, learners will gain an understanding of the Pythagorean theorem and will recognize the variety of ways in which theorems can be proved algebraically, geometrically and visually.
Analyze Math
Analyze Math: Congruent Triangle Problems
The geometry tutorial investigates congruent triangles. The activity has several examples with detailed solutions.
Maths Challenge
Maths challenge.net: Unique Circle Equal Angles
A "three star geometry problem" - requiring the knowledge of biconditional statements and how to prove such problems.
Maths Challenge
Maths challenge.net: Odd Vertices
A "three star geometry problem" requiring knowledge of how to complete geometric proofs. The problem explains what the order of a vertex is and asks for the proof of a generalization.
Maths Challenge
Maths challenge.net: Coloured Strings
A "three star geometry problem" - requiring the knowledge of what a cuboid is and a some knowledge of how to do proofs.
Maths Challenge
Maths challenge.net: Parallelogram Property
A "three star geometry problem" requiring knowledge of how to complete geometric proofs properties of parallelogram.
Maths Challenge
Maths challenge.net: Corner Circle
This is a "three star" geometry problem where prior knowledge of circles and triangles is recommended to solve this circle in the corner problem.
Math Planet
Math Planet: Geometry: Converse of the Pythagorean Theorem and Special Triangles
The converse of the Pythagorean Theorem is examined through examples and a video lesson. [1:04]
Other
Math Court: A Game of Proving Things
This site contains a game to help students better learn how to write proofs. The game has several different levels. The game can be played online or cards and board may be printed and used in the classroom.
Math Planet
Math Planet: Geometry: If Then Statement
If-then statements are explained throught the use of examples and a video lesson. [1:16]
Math Planet
Math Planet: Geometry: Triangles: Inequalities
Gain an understanding of how to list the sides of a triangle in order from shortest to longest by viewing examples and a video lesson. [1:01]
Mangahigh
Mangahigh: Shape: Proof of the Exterior Angle Theorem for a Triangle
Use your knowledge of exterior angles of a triangle to prove the theorem.
Texas Education Agency
Texas Gateway: Using Logical Reasoning to Prove Statements Are True
Given statements about a geometric relationship, the student will distinguish between the undefined terms, definitions, postulates, conjectures, and theorems to prove the statements are true.
Other
Xah Lee: Some Theorems on Rotation and Translation
This site is for the purpose of using proofs for geometry. It helps by giving some useful theorems.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Hyperbolic Geometry
Dr. Math, responds to a question fro a nineth grade stduent who wants to understand hyperbolic geometry. The Dr. uses descriptive analogies in attempts to unravel why triangles in hyperbolic geometry have less than 180 degrees in them.
Education Development Center
Making Mathematics: Proof
This is a site which links to specific techniques of proving including conditional statements, proof by contradiction, mathematical induction, parity arguments, and the pigeonhole principle. The site contains a link to various example...
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: The Value of Two Column Proofs
This site explains why we prove things. The explanation gives real world scenarios and an everyday example of why we should learn how to prove things.
McGraw Hill
Glencoe Mathematics: Self Check Quiz on Reasoning & Proof
The online assessment demonstrates knowledge of concepts utilized in Geometry. The multiple choice questions test students on mathematical reasoning and proof.
Oswego City School District
Regents Exam Prep Center: Theorems and Postulates for Geometry
Here is a partial list of theorems, postulates, and properties.