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Lesson Plan
Shodor Education Foundation

Triangle Area

For Teachers 6th - 9th Standards
While the lesson focuses on right triangles, this activity offers a great way to practice the area of all triangles through an interactive webpage. The activity begins with the class taking a square paper and cutting in in half; can they...
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Lesson Plan
2
2
Curated OER

Two Triangles' Area

For Teachers 7th - 9th Standards
Need an activity for teaching the Pythagorean Theorem? Geometry juniors apply the Pythagorean theorem to two triangles to determine a final calculation. 
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Lesson Plan
EngageNY

An Area Formula for Triangles

For Teachers 11th - 12th Standards
Use a triangle area formula that works when the height is unknown. The eighth installment in a 16-part series on trigonometry revisits the trigonometric triangle area formula that previously was shown to work with the acute triangles....
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Lesson Plan
1
1
Curated OER

Areas of Geometric Shapes with the Same Perimeter

For Teachers 7th - 9th Standards
A triangle, square, hexagon, and circle all have a perimeter of one unit. Eighth graders must attempt to find the area of each and arrange them in order from least to greatest areas. A terrific task for applying four different area...
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Lesson Plan
Alabama Learning Exchange

What You Know About the Bermuda Triangle?

For Teachers 9th - 12th Standards
Get lost in the classifications. Using the backdrop of the Bermuda Triangle, pupils classify it by angle and side measures. They also learn information about the triangle and its history.
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Lesson Plan
Curated OER

Triangles

For Teachers 3rd - 5th
This unit enables scholars to apply the rule for area of a triangle (area equals half base times height). They practice multiplication and division strategies as they calculate areas.
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Lesson Plan
Curated OER

SuperShapes, Part 1; "Tri"ing Triangles

For Teachers 5th - 6th
An outstanding lesson on triangles awaits your math scholars. Learners focus on the triangle, which is the strongest of all polygons. They see the role that triangles play in the design of buildings, and learn about triangle...
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Lesson Plan
Alabama Learning Exchange

Triangle Area: No Height? Use the Sine

For Students 9th - 12th Standards
No height? No problem! Learners use their knowledge and a little help from GeoGebra to develop the Law of Sines formula. The Law of Sines helps to determine the height of triangles to calculate the area.
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Lesson Plan
Illustrative Mathematics

Area of a Trapezoid

For Teachers 7th - 9th Standards
Here is a straightforward example of how to apply the Pythagorean Theorem to find an unknown side-length of a trapezoid. Commentary gives additional information on proving that the inside of the trapezoid is a rectangle, but is...
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Lesson Plan
Government of Hong Kong

Areas and Volumes - 2D Shapes

For Teachers 3rd - 6th Standards
Unfortunately for young mathematicians, the world isn't made entirely of parallelograms, triangles, and trapezoids. After first learning the area formulas for these common shapes, students apply this new knowledge to determine the area...
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Lesson Plan
EngageNY

Using Trigonometry to Determine Area

For Students 9th - 10th Standards
What do you do when you don't think you have enough information? You look for another way to do the problem! Pupils combine what they know about finding the area of a triangle and trigonometry to determine triangle area when they don't...
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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
Illustrative Mathematics

Finding Areas of Polygons, Variation 1

For Teachers 5th - 9th Standards
An exercise in finding the area of polygons by decomposing into triangles and composing into rectangles is the focus of this resource. Make several copies of the worksheet for each participant. Ask learners to use colored pencils to...
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Lesson Plan
Alabama Learning Exchange

Polygons-Changing Area Versus Changing Perimeter

For Teachers 5th - 8th Standards
Investigate the area and perimeter of polygons in this geometry lesson. Young geometers use grid paper to draw a quadrilateral and calculate its area and perimeter. They also read The Greedy Triangle to identify the changing shape of...
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Lesson Plan
Curated OER

Developing Formulas for Triangles and Quadrilaterals

For Teachers 10th
In this geometry worksheet, 10th graders determine the area of triangles, parallelograms, trapezoids, kites, and rhombuses. The one page worksheet contains eleven problems. Answers are included.
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Lesson Plan
Curated OER

Ratios for Area and Volume

For Teachers 5th - 8th
In this ratios for area and volume worksheet, students solve problems where they find the ratios for problems of shapes dealing with area and volume. Students complete 4 problems.
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Lesson Plan
Curated OER

Area of Tangram Pieces

For Teachers 3rd - 4th
Mathematicians calculate the area of a tangram piece without using formulas. They use a geometry journal to record activities during this lesson. They make a set of tangrams and use them to compute area. They use what they discover to...
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Lesson Plan
Hotchalk

Triangle Sum Theorem

For Teachers 8th - 10th Standards
Your visual geometry learners will appreciate triangle drawings as they model the triangle sum theorem and algebraically solve to find the missing interior angle in a triangle. Practice problems increase in complexity and vary in their...
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Lesson Plan
Curated OER

Finding the Area of Shapes

For Teachers 3rd - 5th
In this area of shapes unit, upper graders participate in hands-on problem solving activities to find the formulas for the area of a parallelogram, a triangle, and a trapezoid. They manipulate the geoboard to explore relationships among...
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Lesson Plan
EngageNY

Perimeter and Area of Triangles in the Cartesian Plane

For Students 9th - 12th Standards
Pupils figure out how to be resourceful when tasked with finding the area of a triangle knowing nothing but its endpoints. Beginning by exploring and decomposing a triangle, learners find the perimeter and area of a triangle. They then...
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Lesson Plan
1
1
Illustrative Mathematics

Equal Area Triangles on the Same Base II

For Teachers 9th - 12th Standards
A deceptively simple question setup leads to a number of attack methods and a surprisingly sophisticated solution set in this open-ended problem. Young geometers of different strengths can go about defining the solutions graphically,...
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Lesson Plan
EngageNY

Perimeter and Area of Polygonal Regions in the Cartesian Plane

For Students 9th - 12th Standards
How many sides does that polygon have? Building directly from lesson number eight in this series, learners now find the area and perimeter of any polygon on the coordinate plane. They decompose the polygons into triangles and use Green's...
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Lesson Plan
EngageNY

Real-World Area Problems

For Students 7th Standards
Not all structures take the shape of a polygon. The 21st lesson in a series of 29 shows young mathematicians they can create polygons out of composite shapes. Once they deconstruct the structures, they find the area of the composite figure.
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Lesson Plan
Willow Tree

Surface Area of Three-Dimensional Figures

For Students 8th - 11th Standards
Lateral area and surface area are simple concepts, but calculating them is not as easy! Using formulas, learners calculate lateral area and surface area for the same three-dimensional figures. The resource discusses the formula variables...

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