# Proof by Contradiction Teacher Resources

Find Proof by Contradiction lesson plans and worksheets

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Curated OER

#### Who Dun It?

In this proofs by contradiction instructional activity, students solve 1 word problem about a crime. Students use proof by contradiction to determine the criminal in the word problem.

EngageNY

#### The Converse of the Pythagorean Theorem

Is it a right triangle or not? Introduce scholars to the converse of the Pythagorean Theorem with a lesson that also provides a proof by contradiction of the converse. Pupils use the converse to determine whether triangles with given...

TED-Ed

#### Making Sense of Irrational Numbers

Non-terminating. Non-recurring decimal. Irrational numbers. Proof by Contradiction? Root 2, 3, 5, 6, 7, 8. Don't be afraid to explore the impossible and check out this short video that offers a rational explanation of irrational numbers.

TED-Ed

#### Everything Changed When the Fire Crystal Got Stolen

Viewers of a short video use the Proof by Contradiction technique; to determine which apprentice monk swallowed which crystal the group attempted to steal from the Sacred Crystal Temple.

Curated OER

#### Three for the Money: The Degree/Diameter Problem

Students explore the concept of vertex-edge graphs. In this vertex-edge graphs lesson, students try to construct a graph with a given diameter, number of vertices, size, and planarity. Students construct various vertex-edge graphs with...

Beauty and Joy of Computing

#### Unsolvable and Undecidable Problems

Try as you might, some functions just cannot be computed. The lab introduces the class to the possibility of unsolvable problems. The fourth lesson in a series of seven begins with a logic problem, then progresses to looking at functions...

MinutePhysics

#### The No Cloning Theorem

Perfect cloning is impossible — and that's been proven mathematically. Investigate the complexity of cloning in physics. The video instructor explains why cloning is theoretically impossible. He uses several examples to illustrate the...

Illustrative Mathematics

#### Applying the Pythagorean Theorem in a Mathematical Context

Participants who use this resource will apply the Pythagorean Theorem to show whether or not the shaded triangle inscribed in a rectangle is a right triangle. Once all of the sides on the shaded triangle are found, it is important that...

Curated OER

#### The Truth About Triangles And Proofs

Students engage in a lesson that is about the classification of triangles and the mathematical proofs involved in working with them. They work on a variety of problems that are created by the teacher with the focus upon the importance of...

Curated OER

#### Babylonian Mathematics 2

Students research Babylonian mathematics. They calculate simple surd numbers. Students find the fractional form of rational numbers expressed as decimals. They work with numbers in base 60.