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Lesson Plan
EngageNY

Between-Figure and Within-Figure Ratios

For Teachers 9th - 10th Standards
Tie the unit together and see concepts click in your young mathematicians' minds. Scholars apply the properties of similar triangles to find heights of objects. They concentrate on the proportions built with known measures and solve to...
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Lesson Plan
EngageNY

The Angle-Angle (AA) Criterion for Two Triangles to Be Similar

For Teachers 9th - 10th Standards
What do you need to prove triangles are similar? Learners answer this question through a construction exploration. Once they establish the criteria, they use the congruence and proportionality properties of similar objects to find...
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Lesson Plan
EngageNY

Special Relationships Within Right Triangles—Dividing into Two Similar Sub-Triangles

For Students 9th - 10th Standards
Why are right triangles so special? Pupils begin their study of right triangles by examining similar right triangles. Verifying through proofs, scholars recognize the three similar right triangles formed by drawing the altitude. Once...
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Interactive
Scholastic

Study Jams! Similar Figures

For Students 5th - 8th Standards
Discover how triangles are congruent based on their sides, angles, and proportionality. Learners explore the ways to determine similarity at their own pace, and then they practice afterwards with an assessment. 
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Unit Plan
Massachusetts Department of Education

Similarity through Transformations

For Teachers 9th - 12th Standards
Create the ultimate miniature golf course. The 93-page model curriculum unit from the Massachusetts Department of Elementary and Secondary Education contains nine lessons on understanding similarity in terms of both Euclidean geometry...
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Lesson Plan
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1
Illustrative Mathematics

Bank Shot

For Teachers 9th - 11th Standards
Young geometers become pool sharks in this analysis of the angles and lengths of a trick shot. By using angles of incidence and reflection to develop similar triangles, learners plan the exact placement of balls to make the shot....
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Lesson Plan
2
2
Illustrative Mathematics

Are They Similar?

For Teachers 9th - 11th Standards
Learners separate things that just appear similar from those that are actually similar. A diagram of triangles is given, and then a variety of geometric characteristics changed and the similarity of the triangles analyzed. Because the...
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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
1
1
Illustrative Mathematics

Similar Triangles

For Teachers 9th - 11th Standards
Proving triangles are similar is often an exercise in applying one of the many theorems young geometers memorize, like the AA similarity criteria. But proving that the criteria themselves are valid from basic principles is a great...
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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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Printables
Curriculum Corner

8th Grade Math "I Can" Statement Posters

For Teachers 8th Standards
Clarify the Common Core standards for your eighth grade mathematicians with this series of classroom displays. By rewriting each standard as an achievable "I can" statement, these posters give students clear goals to work toward...
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Printables
Curriculum Corner

8th Grade Math Common Core Checklist

For Teachers 8th Standards
Ensure your eighth graders get the most out of their math education with this series of Common Core checklists. Rewriting each standard as an "I can" statement, this resource helps teachers keep a record of when each standard was taught,...
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Activity
Illustrative Mathematics

Solar Eclipse

For Teachers 9th - 11th Standards
Learners take on the role of astronomers, calculating conditions necessary for a total solar eclipse. Concepts of similar triangles and properties of circles come together as pupils create ratios and use real measurements in determining...
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Lesson Plan
Everyday Mathematics

Mathematics Within: Slope and Triangles

For Teachers 8th - 10th Standards
Learners discover a method for determining the slope of a line by creating and comparing similar triangles. They fold coordinate grids to make three similar triangles then measure the sides to compare the relationships between the...
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Worksheet
Curated OER

Similar Triangles and Trapezoids, and Circles

For Students 9th - 12th
High schoolers answer two problems involving area of shaded regions. Students then answers six questions involving perimeter, area, and circumferences. The remaining two questions involve ratios of similar figures.
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Worksheet
Curated OER

Unit 5: Worksheet 3 - Similar Triangles

For Students 8th - 9th
In this similar triangles activity, students use proportions to solve for the missing sides of similar triangles. This two-page activity contains 16 multi-step problems.
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Unit Plan
Curated OER

Zome System

For Teachers 4th - 6th
Get hundreds of interactive activity plans using the Zome Modeling System. Among dozens of lessons, a first exposure to similar triangles can be very visual for the learner. Here, young geometers explore the number of different shapes...
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Lesson Plan
Curated OER

Geometric Applications

For Teachers 8th - 9th
In this geometry worksheet, students solve 5 word problems. Each of the problems involves finding one side of a right triangle. Story problems relate the Pythagorean Theorem to building ramps, shadows, and the length of a banner.
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Worksheet
Curated OER

Kuta Software - Infinite Geometry: Similar Triangles

For Students 9th - 12th
In this similar triangles activity, students solve 20 short answer problems. Students determine if two given triangles are similar.  Students determine the type of similarity given two triangles. Students are given a sketch of the...
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Worksheet
Curated OER

Glencoe - Proportions and Similar Triangles

For Students 9th - 12th
In this proportions and similar triangles learning exercise, learners solve 14 multiple choice problems. Students find unknown sides of similar triangles using proportions. Learners multiply means and extremes to solve proportions.
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Worksheet
Curated OER

A Geometry Worksheet - Similar Triangles

For Students 9th - 12th Standards
In this similar triangles worksheet, students find the scale factor of 6 sets of similar triangles. Students find the scale factor of two similar triangles given a sketch with measurements. Students use proportions to find a missing side...
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Worksheet
Curated OER

Chapter 8 Extra Problems Worksheet: Similar Triangles

For Students 9th - 12th
In this similar triangles learning exercise, students solve 6 similar triangles. Students use proportions to solve similar triangles and similar rectangles.
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Lesson Plan
Curated OER

Indirect Measurement with Similar Triangles

For Teachers 9th - 12th
Students use similar triangles to find missing heights.  In this using similar triangles to find missing heights lesson plan, students use proportions to find the heights of missing side lengths.  Students find the height of trees and...
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Lesson Plan
Curated OER

Similar Triangles and Proportions

For Teachers 9th - 12th Standards
Pupils investigate similar triangles and proportions as they make conjectures about the length of sides of similar triangles. For this lesson, have your class construct similar triangles using Cabri Jr so that they share a common vertex.