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Lesson Plan
Illustrative Mathematics

Extensions, Bisections and Dissections in a Rectangle

For Teachers 9th - 11th Standards
Gaining practice in translating a verbal description into a diagram and then an equation is the real point of this similar triangles exercise. Once the diagram is drawn, multiple methods are provided to reach the conclusion. An effective...
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Lesson Plan
EngageNY

Similarity and the Angle Bisector Theorem

For Teachers 9th - 10th Standards
Identifying and verifying reproducible patterns in mathematics is an essential skill. Mathematicians identify the relationship of sides when an angle is bisected in a triangle. Once the pupils determine the relationship, they prove it to...
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Instructional Video4:47
Corbett Maths

Construct a 30 Degree Angle

For Students 8th - 11th Standards
Split it down the middle. Using the tools of geometric construction, the video shows two different methods of constructing a 30-degree angle. The first method bisects an angle of an equilateral triangle. The second uses the diagonal of a...
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Worksheet
Curated OER

Making Two-Dimensional Shapes- Matching Worksheet

For Students 1st - 3rd
Now that your learners recognize two-dimensional shapes, can they find what each half of those shapes would look like? There are seven shapes on this worksheet, bisected by a dotted line. Scholars examine these shapes and match them to a...
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Lesson Plan
Curated OER

Perpendicular Segments in a Circle

For Teachers 9th - 12th Standards
High schoolers explore the concept of circles as they construct a circle using a program such as Cabri Jr. Learners construct a chord and a diameter that are perpendicular, then measure the bisected chord and notice that both sides of...
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Worksheet
Curated OER

Making Two-Dimensional Shapes

For Students Pre-K - 1st
Use this introductory geometry instructional activity as a projected warm-up for your class, doing it together and then revealing the explanation on the bottom half. Learners examine a square and a circle, each bisected by a dotted line....
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Worksheet
Curated OER

Reasoning with Rules

For Students 8th - 9th
In this reasoning with rules learning exercise, students solve and complete 12 different problems that include applying various rules to solve the equations given. First, they assume all segments are straight and state the rule used to...
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Lesson Plan
Curated OER

Reflections

For Teachers 5th
Fifth graders create a reflection of a poygon using a Mira. They discover that a line connecting a vertiex of a polygon and the corresponding vertex of its reflection is perpendicular to the line of reflection. Students create a glide...
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Worksheet
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Jesuit High School

Geometry Sample Problems

For Students 8th - 11th Standards
I'd like to prove that this worksheet has a lot to offer. Seven problems using triangles and parallelograms practice the traditional method of a two-column proof. After the worksheet is some practice problems that show worked out...
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Unit Plan
Mathematics Vision Project

Circles: A Geometric Perspective

For Teachers 10th - 12th Standards
Circles are the foundation of many geometric concepts and extensions - a point that is thoroughly driven home in this extensive unit. Fundamental properties of circles are investigated (including sector area, angle measure, and...
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Handout
Mt. San Antonio Collage

Congruent Triangles Applications

For Students 9th - 12th Standards
Triangles are all about threes, and practicing proving postulates is a great way to get started. The first page of the worksheet provides a brief introduction of the different properties and postulates. The remaining pages contain...
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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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Lesson Plan
Curated OER

Geometry Practice: G.G.28 #1: Congruent Triangles

For Teachers 9th - 12th
In this congruent triangles worksheet, students solve four multiple choice problems. Students determine which statement is the appropriate reasoning to say that two triangles are congruent.
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Worksheet
Curated OER

Picking Patterns

For Students 4th - 6th
In this pattern worksheet, students enumerate the number of objects that comes next in the sequence including triangles, blocks, and circles. There are 6 questions.
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Worksheet
Geometry Accelerated

Accelerated Geometry Review Sheet

For Students 8th - 10th Standards
Your geometry learners use their knowledge of various geometric concepts to write proofs. Starting with givens containing parallel line segments with transversals and triangles and quadrilaterals, and the mid-point and distance formulas;...
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Worksheet
Mt. San Antonio Collage

Isosceles Triangles and Special Line Segments

For Students 9th - 12th Standards
Under which conditions can a triangle be classified as isosceles? High schoolers practice identifying isosceles triangles and special line segments, including angle bisectors, medians of triangles, and perpendicular bisectors of sides of...
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Lesson Plan
EngageNY

Circles, Chords, Diameters, and Their Relationships

For Teachers 9th - 10th Standards
A diameter is the longest chord possible, but that's not the only relationship between chords and diameters! Young geometry pupils construct perpendicular bisectors of chords to develop a conjecture about the relationships between chords...
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Lesson Plan
EngageNY

Copy and Bisect an Angle

For Teachers 9th - 10th Standards
More constructions! In this third installment of a 36-part series, learners watch a YouTube video on creating door trim to see how to bisect an angle. They then investigate how to copy an angle by ordering a given list of steps.
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Lesson Plan
EngageNY

End-of-Module Assessment Task - Geometry (module 1)

For Students 9th - 10th Standards
Have you hit a wall when trying to create performance task questions? Several open-ended response questions require a deep level of thinking. Topics include triangle congruence, quadrilaterals, special segments, constructions, and...
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Lesson Plan
EngageNY

Characterize Points on a Perpendicular Bisector

For Students 9th - 10th Standards
Learn transformations through constructions! Pupils use perpendicular bisectors to understand the movement of a reflection and rotation. They discover that the perpendicular bisector(s) determine the line of reflection and the center of...
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Worksheet
Curated OER

Proofs

For Students 8th - 11th
In this geometric proof worksheet, students compose 20 triangle congruency proofs. Students will decide if there is enough information in problems 1-6 to prove if any triangles are congruent. In problems 17 to 20, students use given...
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Lesson Plan
Curated OER

Proving Quadrilateral Properties

For Teachers 9th - 11th
Working backwards can sometimes help you see a path to solving a problem. In this chapter, properites of quadrilaterials are proven by looking at flowcharts and working the probem backwards. Worked through examples are given, along with...
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Worksheet
Curated OER

Tangents, Secants, and Chords

For Students 10th
In this tangents, secants and chords worksheet, 10th graders identify and solve 48 different problems that include using 3 different theorems for defining circles. First, they determine the area of each circle with C as the center and a...
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Worksheet
Curated OER

Chapter 5 Final Review Extra Problems. Triangles

For Students 10th - 12th
In this triangles worksheet, students identify the median, altitude, segment, angle bisector, perpendicular bisector and triangle midsegment of triangles.  They find the perimeter of triangles.  This three-page worksheet contains 8...