Illustrative Mathematics
Lines of Symmetry for Triangles
What can symmetry tell us about triangles? After looking at four examples, learners will come to realize that lines of symmetry are different for equilateral, isosceles, and scalene triangles. Use this guided practice activity as an...
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The Pythagorean Theorem and Classifying Triangles
Through the examination of the relationship between the lengths of the sides of a triangles learners will learn the classification of triangles (acute, right, or obtuse).
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Toothpick Triangles
Students draw a chart (included in the lesson) to use with their investigation. They review terminology of triangles and receive toothpicks to use in the lesson. Beginning with three toothpicks, students form a triangle. They complete...
Illustrative Mathematics
Are These Right?
Is that a right triangle or a wrong triangle? Young mathematicians look at eleven different shapes and use a measuring tool of their choice to determine which triangles have right angles. Consider cutting out sets of the shapes to...
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Exploring Polygons and The Greedy Triangle
Excellent activity! Anne Linehane's geometry story, The Greedy Triangle, offers an opportunity to practice forming various types of polygons with your learners. Using elastic bands (or Chinese jump ropes),...
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Triangle Inequality Theorems Investigation
Students estimate and measure triangles. In this geometry lesson, students identify the relationship between three sides and a triangle. They use the inequality theorem to decide if a triangle will be formed or not.
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Exploring Geometric Figures
Tenth graders explore mathematics by participating in hands-on daily activities. Learners identify a list of different shapes and classify them by shape, size, sides and vertices. They utilize tangrams and geometric pieces to gain...
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Triangle Inequality Theorem
Learners use the inequality theorem to solve triangles and their properties. In this geometry instructional activity, students are given spaghetti of different lengths and asked to create triangles. They conclude the necessary length...
Illustrative Mathematics
All vs. Only Some
All shapes have certain defining attributes that set them apart from others. In order to understand this, young mathematicians look at examples and non-examples of triangles, rectangles, and squares, working as a whole class to create...
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Obtuse Triangles
Fourth graders explore obtuse triangles. In this geometry instructional activity, 4th graders make obtuse triangles with paper and scissors. They determine how to find the center of their triangle.
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Similar and Congruent Triangles
Students create and classify different types of triangles using an online geo-board. They explore the concepts of similar and congruent as they discover how to draw similar and congruent triangles.
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Review of Triangles
Learners investigate the Pythagorean Theorem. In this geometry instructional activity, students define angles and sides of right triangles. They calculate the area and surface area using formulas derived by the Pythagorean Theorem.
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Triangles Introduction
Students explore geometry by drawing various shapes in class. In this triangle characteristics lesson, students identify the attributes that classify a shape as a triangle and practice using their bodies to create triangles in class....
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Angles in Triangles
Eighth graders translate word problems using mathematical ideas. In this geometry lesson, 8th graders identify angles of triangles using equations and the triangle sum theorem. They create angles with a protractor and straight edge.
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Fractals
Students explore the concept of fractals. In this fractal lesson, students use applets to explore Koch's Snowflake, Sierpinski's Triangle, and other fractals. Students develop these concepts through exploration and teacher guided...
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Pythagorean Relationships
Oh that Pythagorean Theorem is so useful. Learners engage in a 45 minute learning activity that requires them to solve for missing angles and sides of a right triangle. They'll use the Pythagorean Theorem to find the rations of sides and...
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Quadrilateral Attributes
Students classify quadrilaterals. In this quadrilateral lesson, students identify the characteristics of quadrilaterals. They write their findings in a journal. Students use geoboards to create quadrilaterals from given descriptions.
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CSI Investigation of Congruence and Similarity
Pupils differentiate between similarity and congruence using polygons. In this geometry lesson, students label triangles based on their properties. They find missing sides and angles using the interior sum theorem.
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Geometry and Measurement
Students view a right triangle displayed by the teacher. Students measure legs and the interior angles of the triangle. They look for a pattern or relationship between the legs and angles. Students use pegboards and string to create more...
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The Search for Pythagoras' Treasure
Students identify and define properties of triangles. In this geometry lesson plan, students identify the missing sides and angles of right triangles. They use the rules of the Pythagorean Theorem to solve their problems.
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Compare 2-D Shapes
Second graders explore and analyze plane shapes. In this plane shapes instructional activity, 2nd graders evaluate shape attributes to classify shapes correctly. Students work in groups to create different shapes.
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Pythagorean Theorem by Graphic Manipulation
There are many different ways to show a proof of the Pythagorean Theorem. Here is a nice hands-on paper cutting activity that shows a graphic representation. You can even challenge your young Pythagoreans to come up with their own...
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Properties of Parallelograms
Students identify different properties of parallelograms. In this geometry lesson, students complete problems that proves the theorems and properties of parallelograms. They graph the different shapes on paper.
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Powerful Polygons
Students scan the classroom to find different common shapes. They listen as the teacher defines polygon and regular polygon. The teacher demonstrates regular polygons via the Internet and the "Math is Fun" web site. Students go outside...