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Worksheet
Curated OER

Proving Figures Congruent

For Students 10th
In this proving figures congruent worksheet, 10th graders solve and complete 11 different problems. First, they determine the additional information needed to prove the triangles congruent. Then, students determine which postulate, if...
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Lesson Plan
Curated OER

Building Congruent Triangles

For Teachers K - 12th
Students differentiate between congruent and similar triangles. In this geometry lesson, students identify the lengths and angle measures of triangles. They use postulates to prove their answers.
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Interactive
CK-12 Foundation

Distance Between Two Points: Segment Addition

For Students 9th - 12th Standards
Examine the segment addition postulate through an online simulation activity. An interactive lesson allows scholars to manipulate points and watch as the lengths of segments change. Through their study, they are able to apply the Segment...
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Lesson Plan
Illustrative Mathematics

Joining Two Midpoints of Sides of a Triangle

For Teachers 9th - 11th Standards
Without ever using the actual term, this exercise has the learner develop the key properties of the midsegment of a triangle. This task leads the class to discover a proof of similar triangles using the properties of parallel lines cut...
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Lesson Plan
EngageNY

Triangle Congruency Proofs (part 1)

For Teachers 9th - 10th Standards
Can they put it all together? Ninth graders apply what they know about proofs and triangle congruence to complete these proofs. These proofs go beyond the basic triangle congruence proofs and use various properties, theorems, and...
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Interactive
CK-12 Foundation

Angle Measurement: Adding Angles

For Students 9th - 12th Standards
Build angles from angles. Using the Angle Addition Postulate, learners find the measures of unknown angles. The interactive simulation shows a visual representation of the postulate and allows individuals to manipulate the angles and...
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Lesson Plan
Virginia Department of Education

Similar Triangles

For Teachers 9th - 11th Standards
Pupils work in pairs to investigate what it takes to prove that two triangles are similar. They work through various shortcuts to find which are enough to show a similarity relationship between the triangles. Small groups work with the...
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Lesson Plan
Curated OER

Similarity and Congruence

For Teachers 9th - 12th
Students determine that two figures are similar or congruent by investigating figures that are similar and figures that are congruent. They prove that two figures are similar or congruent by using definitions, postulates, and theorems.
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Unit Plan
Mathematics Vision Project

Geometric Figures

For Teachers 10th - 12th Standards
Logical thinking is at the forefront of this jam-packed lesson, with young mathematicians not only investigating geometric concepts but also how they "know what they know". Through each activity and worksheet, learners wrestle with...
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Lesson Plan
Virginia Department of Education

Congruent Triangles

For Teachers 9th - 11th Standards
Is this enough to show the two triangles are congruent? Small groups work through different combinations of constructing triangles from congruent parts to determine which combinations create only congruent triangles. Participants use the...
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Lesson Plan
Curated OER

Angles and Arcs

For Teachers 9th - 10th
Students discuss the sum of central angles and use string to create them on circles. They find the measure and length of both minor and major arcs. Students give examples of concentric, similar, and congruent circles and congruent arcs.
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Lesson Plan
Curated OER

Congruent Triangles

For Teachers 9th - 12th
Learners explore the concept of congruent triangles.  In this congruent triangles lesson, students use Cabri Jr. to construct two congruent triangles using circles.  Learners determine if the two triangles are congruent by using the SSS,...
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Interactive
Curated OER

Proofs with Triangles Self-check Practice

For Students 8th - 10th
In this triangle theorems worksheet, students identify the theorem used to prove the specified triangular relationship. Students are shown an illustration of two or more triangles. They identify the postulate that would be used to prove...
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Lesson Plan
Curated OER

Similar Triangles

For Teachers 9th
Ninth graders find the height of every day objects using techniques learned through postulates that allow triangles in a problem to be similar. They calculate the length of a missing side and solve proportions.
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Worksheet
Curated OER

Euclidean Geometry

For Students 9th - 12th
In this Euclidean geometry worksheet, students use a straight edge and a compass to create constructions that are possible with Euclid's Postulates. This one-page worksheet contains two construction problems.
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Worksheet
Curated OER

Proving Lines Parallel

For Students 10th
In this proving lines parallel learning exercise, 10th graders solve 10 different types of problems that prove that various lines are parallel to each other. First, they find the value of x so that line a is parallel to line b. Then,...
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Lesson Plan
Harvard University

The Nouns of Geometry

For Teachers 9th - 12th
Socratic questioning to teach Euclidean geometry? "The Nouns of Geometry," followed by "The Verbs of Geometry," and the misfit, "A Beginner's Story - The Equilateral Triangle" are designed to encourage learners to explore various topics...
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Instructional Video11:40
2
2
Flipped Math

Properties of Parallel Lines

For Students 9th - 12th Standards
Work within a parallel universe. Scholars learn about the relationships of angles when two parallel lines are intersected by a transversal. They see how to find the measurements of all eight angles by knowing the measure of one angle....
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Assessment
Mathed Up!

Loci and Constructions

For Students 8th - 11th Standards
A General Certificate of Secondary Education math review has class members make basic constructions. Using a protractor and a ruler along with a compass, pupils develop drawings of triangles with given measurements. Scholars use their...
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Instructional Video6:57
2
2
Flipped Math

Unit 2 Review: Reasoning and Proofs

For Students 9th - 12th Standards
The proof is in the review. Individuals watch a short review of the content from the unit to prepare for the unit exam. The review covers inductive reasoning, conditional and related statements, and two-column algebraic and geometric...
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Instructional Video5:17
2
2
Flipped Math

Unit 3 Review: Parallell and Perpendicular Lines

For Students 9th - 12th Standards
Learners watch a quick review on the Parallel and Perpendicular Lines unit. The pupils work through ten review problems ranging from identifying types of angles formed by parallel lines and transversals to writing equations of parallel...
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Worksheet
Curated OER

Measuring Angles

For Students 10th
In this measuring angles worksheet, 10th graders solve and complete 8 various types of problems. First, they use a protractor to find the measure of each angle shown. Then, students find the missing angle measures. They also refer to the...
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Assessment
Math Worksheets Center

Congruent Triangle Proofs Quiz

For Students 9th - 12th
A congruent triangles quiz challenges teenage mathematicians to complete a pair of geometric proofs. Each problem includes a picture of the triangles in question, a given set of information, and the five steps needed to finish the proof....
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Lesson Plan
Curated OER

Measuring Length: Practice A

For Teachers 9th
Ninth graders investigate the segment addition postulate.  In this geometry instructional activity, 9th graders explore the difference between equal and congruent in relation to segment length.  The instructional activity includes an...

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