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Worksheet
Curated OER

Triangles

For Students 10th
In this geometry worksheet, 10th graders solve problems involving triangular inequality. They apply the proofs and theorem of triangles to solve these problems. There is an overview and one question.
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Worksheet
Curated OER

Angles in Polygons

For Students 10th
In this geometry activity, 10th graders solve problems involving quadrilaterals using the angle sum of quadrilaterals. They solve for linear pairs, opposite angle theorem and triangular angles. There are 5 questions.
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Lesson Plan
Curated OER

Which Quadrilateral Is It?

For Teachers 9th - 12th
Young scholars prove conjectures about geometric figures on the plane or in space using coordinate geometry. They develop fluency in operations with real numbers, vectors and matrices using mental computation or paper-and-pencil...
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Lesson Plan
Curated OER

Distance Formula

For Teachers 1st - 11th
Students calculate the distance between two points using the distance formula. In this geometry lesson, students derive the distance formula using the Pythagorean Theorem.
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Lesson Plan
Curated OER

Regular Polyhedra

For Teachers 10th
Tenth graders investigate the history of geometry and its different shapes. In this geometry lesson, 10th graders practice seeing three dimensional shapes and explain why there are only five polyhedra. They relate all the new materials...
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Lesson Plan
Curated OER

Why Doesn't SSA Work?

For Teachers 10th - 11th
Students investigate the relationship between angles and their sides. In this geometry lesson, students prove why SSA does not work as a true angle side relationship theorem.
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Lesson Plan
Curated OER

Parallel and Perpendicular Lines

For Teachers 10th
Tenth graders explore parallel and perpendicular lines.  In this geometry instructional activity, 10th graders investigate the relationships associated with parallel lines and transversals, perpendicular lines, and the angles formed by...
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Lesson Plan
Curated OER

Proving that You Have Found the Minimum

For Teachers 10th
Tenth graders pretend to set up an ice cream shop in a make believe town of shapes.  In this geometry lesson, 10th graders work together to put up an ice cream stand in an ideal location and solve for the minimum given the shapes.
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Lesson Plan
Curated OER

Triangle Sum Theorem

For Teachers 10th
Tenth graders investigate the theorems of angles and lines to prove triagle sum theorem. In this geometry lesson, 10th graders discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two...
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Lesson Plan
Curated OER

Investigating AAS

For Teachers 9th - 10th
Students investigate the theorems of ASA, AAS, AAA and ASA. In this geometry lesson, students discuss the theorems of triangles and how it is used to solve for missing sides or angles. They review how two angles are formed by two rays...
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Lesson Plan
Curated OER

Deductive and Inductive Reasoning

For Teachers 9th - 10th
Students differentiate between inductive and deductive reasoning. In this geometry instructional activity, students identify congruent figures and examine logos for congruency.
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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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Assessment
Inside Mathematics

Circles in Triangles

For Teachers 9th - 12th Standards
Challenge the class with inscribed circles in triangles. The assessment task requests class members use their knowledge of circles and right triangles to prove two triangles are congruent. They go on to utilize their knowledge of...
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Lesson Plan
Virginia Department of Education

Circles in the Coordinate Plane

For Teachers 9th - 11th Standards
Make the connection between the distance formula and the equation of a circle. The teacher presents a lesson on how to use the distance formula to derive the equation of the circle. Pupils transform circles on the coordinate plane and...
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Assessment
Mathematics Assessment Project

Square

For Students 8th - 12th Standards
Don't be a square! Young mathematicians determine the slope and length of a line segment. They then prove whether four given coordinate points form a square.
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Worksheet
Curated OER

Points, Lines and Planes

For Students 10th
For this points, lines and planes worksheet, 10th graders solve and complete 9 various types of problems. First, they name the planes that intersect a figure shown. Then, students determine the points that are collinear and coplanar in...
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Worksheet
Curated OER

Challenge: Skills and Applications Lesson 1.3

For Students 10th - 12th
In this skills worksheet, students explain the Segment Addition Postulate, provide examples and counter examples and determine congruent line segments.  This one-page worksheet contains 11 multi-step problems.
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Lesson Plan
West Contra Costa Unified School District

Investigating Special Right Triangles

For Teachers 9th - 12th
Scholars first investigate relationships in the side lengths of 30°-60°-90° triangles and 45°-45°-90° triangles. This knowledge then helps them solve problems later in the lesson plan about special right triangles.
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Lesson Plan
EngageNY

Inscribed Angle Theorem and Its Applications

For Teachers 9th - 10th Standards
Inscribed angles are central to the lesson. Young mathematicians build upon concepts learned in the previous lesson and formalize the Inscribed Angle Theorem relating inscribed and central angles. The lesson then guides learners to prove...
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Lesson Plan
EngageNY

Tangent Segments

For Teachers 9th - 12th Standards
What's so special about tangents? Learners first explore how if a circle is tangent to both rays of an angle, then its center is on the angle bisector. They then complete a set of exercises designed to explore further properties and...
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Lesson Plan
West Contra Costa Unified School District

Pythagorean Theorem and Its Converse

For Teachers 9th - 12th Standards
Challenge scholars to prove the Pythagorean Theorem geometrically by using a cut-and-paste activity. They then must solve for the missing sides of right triangles.
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Lesson Plan
EngageNY

Three-Dimensional Space

For Teachers 9th - 10th Standards
How do 2-D properties relate in 3-D? Lead the class in a discussion on how to draw and see relationships of lines and planes in three dimensions. The ability to see these relationships is critical to the further study of volume and other...
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Lesson Plan
EngageNY

Unknown Angle Problems with Inscribed Angles in Circles

For Teachers 9th - 10th Standards
We know theorems about circles—now what? Class members prove a theorem, with half the class taking the case where a point is inside the circle and half the class taking the case where a point is outside the circle. The lesson then...
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Lesson Plan
EngageNY

Construct an Equilateral Triangle (part 2)

For Teachers 9th - 10th Standards
Triangles, triangles, and more triangles! In this second installment of a 36-part series, your young mathematicians explore two increasingly challenging constructions, requiring them to develop a way to construct three triangles that...

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