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Interactive
CK-12 Foundation

Logarithms: Logarithm Triangle

For Students 10th - 12th Standards
Study logarithmic properties using a triangle. A clever manipulative shows how a triangle can represent the three parts of a logarithmic or exponential equation. Pupils review the concept and then answer guiding questions to further...
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Lesson Plan
Curated OER

SAS Similarity Theorem

For Teachers 9th - 10th
Students identify and use the similarity theorem. In this geometry lesson, students differentiate between congruent and similar triangles. They solve problems using the computer modifying shapes by dragging.
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Lesson Plan
Curated OER

Does Your Field Measure Up

For Teachers 9th - 11th
Students measure angles using a plane table kit. In this geometry lesson, students use trigonometric identities to find the values of the length of a football field.
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Lesson Plan
Curated OER

Triangle Inequality Theorem

For Teachers 8th - 10th
Students use the inequality theorem to solve triangles and their properties. In this geometry lesson, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length needed to make a...
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Lesson Plan
Curated OER

Investigating Trigonometric Ratios Through Similar Right Triangles

For Teachers 9th - 10th
Students identify similar and congruent right triangles. In this geometry lesson, students use trigonometric ratios to identify missing sides and angles of a triangle. They differentiate similar and congruent triangles.
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Lesson Plan
Curated OER

Angles and Similarity

For Teachers 9th - 12th Standards
Students identify triangles as similar or congruent. In this geometry lesson plan, students drag triangles around on the navigator to see the effect of different angles on the shape of the triangle. They discuss angle similarity and...
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Lesson Plan
Curated OER

The Sierpinski Triangle

For Teachers 9th - 10th
Students investigate the Sierpinski triangle. In this geometry lesson plan, students define fractal curves and its relationship to triangles. They identify repeating sequences and relate it to fractals.
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Lesson Plan
Curated OER

Similarity and Congruence

For Teachers 9th - 12th
Students explore the concept of similarity and congruence. In this similarity and congruence instructional activity, students cut out strips of paper and form a triangle. Students try to prove that their triangles are congruent using the...
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Lesson Plan
Curated OER

Measuring Heights With Triangles

For Teachers 8th - 10th
Students identify the different properties of triangles. In this geometry lesson, students differentiate between congruent and similar triangles. They use mathematical reasoning to solve word problems.
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Lesson Plan
Curated OER

Triangle Congruence

For Teachers 9th - 11th
Students use web applet to create congruent triangles. In this geometry lesson, students differentiate between congruent and similar. They create shapes online and drag those shapes around to create visuals of triangles.
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Lesson Plan
Curated OER

Ratios of Similar Figures

For Teachers 9th - 12th Standards
Students identify the ratios of different triangles. In this geometry lesson, students identify the similarity and differences of triangles. They use the navigator to move the sides of the triangle around.
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Lesson Plan
Curated OER

Congruent Triangles

For Teachers 9th - 12th Standards
High schoolers identify properties of triangles. In this geometry lesson, students differentiate between similar and congruent triangles. They use the umber of sides to help define the angle of the polygon.
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Lesson Plan
Curated OER

Congruent and Similar figures

For Teachers 8th
Eighth graders explore congruent and similar figures.  In this eighth grade geometry lesson, 8th graders use geoboards to create congruent and similar figures and explore the relationships between the sides and angles. 
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Lesson Plan
Curated OER

Triangles in Architecture

For Teachers 10th - 12th
Students find triangles in the real world. In this geometry lesson, students analyze and identify properties of two and three-dimensional objects. They differentiate between similarity and congruence.
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Lesson Plan
Curated OER

Obtuse Triangles

For Teachers 4th
Fourth graders explore obtuse triangles. In this geometry lesson, 4th graders make obtuse triangles with paper and scissors. They determine how to find the center of their triangle.
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Lesson Plan
Curated OER

Geometry

For Teachers 9th - 11th
Learners are introduced to the basics of Geometry. Using cutout shapes, they identify whether they are polygons by using the properties of polygons. They practice drawing shapes they are going to be using on an everyday basis and...
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Lesson Plan
Futures Channel

Folding Circles

For Teachers 7th - 12th Standards
Young scholars investigate properties of circles. For this geometry lesson, students differentiate between similarity and congruence as they observe polygons. They investigate properties of two and three dimensional shape.
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Lesson Plan
Curated OER

Triangles with Collinear Circumcenters

For Teachers 9th - 10th
Pupils 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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Lesson Plan
Curated OER

Constructing Midsegments of Triangles

For Teachers 9th - 10th
Students construct midsegments. In this geometry lesson, students make conjectures and apply properties of triangles to solve problems. They complete an activity on the computer.
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Lesson Plan
Curated OER

Investigating Trigonometric Ratios Through Similar Right Triangles.

For Teachers 8th - 10th
49Students investigate the properties of right triangles. In this geometry lesson, students differentiate between similar and congruent triangles. They use the Pythagorean Theorem to find the missing angles and sides.
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Lesson Plan
Curated OER

Investigating the Sierpinski Triangle

For Teachers 9th - 11th
Students solve and analyze the sierpinski's triangle. In this geometry lesson, students identify properties and theorem of triangles. They solve problems involving angles and sides of triangles.
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Lesson Plan
Curated OER

Why can't We Use SSA to Prove Triangles Congruent?

For Teachers 9th - 10th
Students investigate triangles and congruences. In this geometry lesson, students differentiate between inductive and deductive reasoning. They differentiate between similar and congruent triangles.
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Lesson Plan
Curated OER

Pedal Triangles

For Teachers 8th - 10th
Students identify the properties and theorems of triangles. In this geometry lesson, students construct angle bisectors using a compass and straight edge. They identify triangular similarity and congruency.
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Lesson Plan
Curated OER

The Minimal Distance Point from the Vertices of a Triangle

For Teachers 9th - 10th
Students calculate the distance from the vertex of a triangle to the center. In this geometry lesson, students find the shortest distance between a point and the vertex of a triangle. They relate this concept of distance to the real world.