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Worksheet
Curated OER

Geometric Concepts and Polygons

For Students 9th - 11th
In this geometry worksheet, students identify the altitude, perpendicular bisector, median, angle bisector and the area of different polygons. There are 33 problems.
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Lesson Plan
Curated OER

Contructions and Conjectures

For Teachers 10th - 11th
Students make constructions and conjectures. In this geometry lesson, students construct right, acute and obtuse angles using a straight edge and a protractor. They investigate parallel lines and the angles formed by the angles.
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Lesson Plan
Curated OER

Isosceles Triangles

For Teachers 9th - 10th
Students identify the properties of an isosceles triangle. In this geometry lesson, students find the midpoint, median and angle bisector of a triangle. They construct angle bisectors and measure missing angles.
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Lesson Plan
Curated OER

Incenter of a Triangle

For Teachers 10th
Tenth graders find the incenter of a triangle. For this geometry lesson, 10th graders define the way to create an incenter with an angle bisector. They differentiate between incenter and incircle.
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Worksheet
Curated OER

Concurrent Lines, Medians and Altitudes

For Students 9th - 10th
In this geometry instructional activity, students construct angles and identify medians and altitudes. They use a compass and protractor to perform heir construction. There are 28 questions.
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Lesson Plan
Curated OER

Concurrent Lines in Triangles

For Teachers 9th - 12th
Students explore the concept of concurrent lines in triangles. In this concurrent lines in triangles lesson plan, students work in groups to investigate properties of concurrent lines in acute, right, and obtuse triangles. Students use a...
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Lesson Plan
Curated OER

Triangles with Collinear Circumcenters

For Teachers 9th - 10th
Students identify the circumcenter of a triangle. In this geometry lesson, students construct a perpendicular bisector using a straight edge and a compass. They differentiate between triangles and collinear points.
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Handout
Lockport City School District

Reasons for Geometric Statement/Reason Proofs

For Students 8th - 11th Standards
Stuck trying to remember the formal language of a geometric proof? Never fear, this handout has them all ready to go. The reasons are sectioned by topic so this handy guide is ready when you are to tackle those two column proofs. 
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Unit Plan
Mathematics Vision Project

Module 6: Congruence, Construction, and Proof

For Teachers 8th - 10th Standards
Trace the links between a variety of math concepts in this far-reaching unit. Ideas that seem very different on the outset (like the distance formula and rigid transformations) come together in very natural and logical ways. This unit...
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Worksheet
Curated OER

Regents Exam Questions G.G.21: Centroid, Orthocenter, Incenter, and Circumcenter

For Students 9th - 12th
In this triangles instructional activity, students solve 4 multiple choice problems. Students find the centroid, orthocenter, incenter, and circumcenter or various triangles.
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App
Bytes Arithmetic

Geometry Pad+

For Students 6th - 10th Standards
Graphing paper, pencil, ruler, protractor, and compass, all get replaced or supplemented with this dynamic geometry application. Here, you can create, move, and scale many different shapes, as well as, explore and change their properties...