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Lesson Plan
EngageNY

More About Similar Triangles

For Teachers 8th Standards
Determine whether two triangles are similar. The lesson presents opportunities for pupils to find the criterion needed to show that two triangles are similar. Scholars use the definition of similarity to find any missing side...
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Lesson Plan
Curated OER

Tile Patterns I: Octagons and Squares

For Teachers 7th - 9th Standards
This can be used as a critical thinking exercise in congruence or as a teaching tool when first introducing the concept. Four octagons are arranged in such a way that a square is formed in the middle. With this information, geometry...
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Lesson Plan
Virginia Department of Education

How Many Triangles?

For Teachers 9th - 11th Standards
Something for young mathematicians to remember: the sum of any two sides must be greater than the third. Class members investigates the Triangle Inequality Theorem to find the relationship between the sides of a triangle. At the same...
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Assessment
Inside Mathematics

Rhombuses

For Teachers 9th - 12th Standards
Just what does it take to show two rhombuses are similar? The assessment task asks pupils to develop an argument to show that given quadrilaterals are rhombuses. Class members also use their knowledge of similar triangles to show two...
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Assessment
Concord Consortium

Isosceles Triangle Spaces

For Students 7th - 10th Standards
How many different types of triangles can your class name? A discovery lesson guides learners through an exploration of the different triangle types and the relationships between their angles and sides. Using coordinate geometry,...
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Activity
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Illustrative Mathematics

Midpoints of the Sides of a Paralellogram

For Teachers 9th - 12th Standards
This task asks learners to prove that the segment joining the midpoints of two sides of a parallelogram is both congruent and parallel to an adjacent side of the parallelogram. The activity would be good to use in a discussion about how...
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Assessment
Inside Mathematics

Hopewell Geometry

For Teachers 9th - 12th Standards
The Hopewell people of the central Ohio Valley used right triangles in the construction of earthworks. Pupils use the Pythagorean Theorem to determine missing dimensions of right triangles used by the Hopewell people. The assessment task...
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Assessment
Inside Mathematics

Quadrilaterals

For Teachers 9th - 12th Standards
What figure is formed by connecting the midpoints of the sides of a quadrilateral? The geometry assessment task has class members work through the process of determining the figure inscribed in a quadrilateral. Pupils use geometric...
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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
EngageNY

Modeling Using Similarity

For Teachers 8th Standards
How do you find the lengths of items that cannot be directly measured? The 13th installment in a series of 16 has pupils use the similarity content learned in an earlier resource to solve real-world problems. Class members determine...
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Lesson Plan
Curated OER

Why Does ASA Work?

For Teachers 9th - 10th Standards
Your geometry learners explore Angle-Side-Angle congruence in this collaborative task. The sum of the interior angles of all triangles being one hundred eighty degrees, is the key learners will discover as they explain their reasoning...
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Lesson Plan
Curated OER

Finding the Area of an Equilateral Triangle

For Teachers 9th - 11th Standards
The problem seems simple: find the area of the equilateral triangle whose sides are each length 1. In fact, this same problem is solved in 8th grade, addressing a different Common Core standard, using the formula for area of a triangle...
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Lesson Plan
Curated OER

When Does SSA Work to Determine Triangle Congruence?

For Teachers 9th - 10th Standards
Your learners will make good use of the Socratic method in a collaborative task that begins with an assumed solution and ends with deeper understanding of the idea of determining two triangles congruent.
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Assessment
Concord Consortium

Rectangle Space

For Students 9th - 12th Standards
Take a coordinated look at rectangles. The task asks pupils to plot the length and width of created triangles in the coordinate plane. Using their plots, scholars respond to questions about rectangles and their associated points on the...
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Lesson Plan
Illustrative Mathematics

Base and Height

For Teachers 5th - 7th Standards
It is easy to find the area of a triangle where the base and the height are given. But in this resource, it is up to your geometers to identify the base and height of the triangle. In fact, your pupils will learn that there are three...
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Assessment
Noyce Foundation

Parallelogram

For Teachers 6th - 7th Standards
Parallelograms are pairs of triangles all the way around. Pupils measure to determine the area and perimeter of a parallelogram. They then find the area of the tirangles formed by drawing a diagonal of the parallelogram and compare their...