Curated OER
Measuring Angles in a Triangle
High schoolers investigate the sum of the measures of the angles of a triangle. They draw a triangle and measure the interior angles. Using Cabri Jr., learners find the sum of the measures of the interior angles. The activity provides an...
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Nested Similar Triangles
Nested triangles have been created so that they share a common vertex and vertex angle. Learners drag the endpoints of the side that is opposite the common angle to discover the conditions that make the nested triangles similar. When...
Curated OER
Circumscribing a Circle About a Triangle
Pupils circumscribe a circle about a triangle. They construct a triangle using Cabri Jr and then circumscribe it. They then use knowledge of perpendicular bisectors and circumcenters to locate the center of the circle and then...
Curated OER
Exploring the Circumcenter of a Triangle
Students construct the circumcenter of a triangle. For this constructing the circumcenter of a triangle lesson, students construct a triangle using Cabri Jr. Students draw perpendicular bisectors of the sides of the triangle. Students...
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Investigating Segments in a Right Triangle
High schoolers explore the concept of right triangles as they construct a right triangle using Cabri Jr. Learners find the midpoint of the hypotenuse and construct a line from the midpoint to the vertex of the right angle. They then...
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Exploring the Orthocenter of a Triangle
Young mathematicians explore the concept of triangles as they construct altitudes of triangles to find the orthocenter. Learners construct their triangles using Cabri Jr. on their graphing calculators and find that the altitudes of a...
Curated OER
Midsegments of a Triangle
Students analyze midsegments of triangles in this instructional activity. They use Cabri Jr. software to observe the relationships between interior angles and midsegments of triangles. Specific instructions for creating this...
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Triangle Sum Theorem
Teach your class how to solve problems using the triangle sum theorem. In this geometry instructional activity, students identify the missing angles in a triangle using the sum theorem. They graph triangles on the TI and moves the sides...
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Constructions Triangles
Learners explore the difference between a construction and a drawing. They focus on various ways to construct different types of triangles. The lesson is an application of Cabri Jr. and reinforces the difference between a constructions...
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Ratios in Right Triangles
Learners calculate the sides of right triangles in this trigonometric ratios lesson. They use Cabri Jr. software and TI-83 or TI-84 calculators to find the side lengths and their ratios to each other for various triangles. The provided...
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Similar Triangles and Proportions
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.
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Triangle Inequality Theorem
High schoolers investigate the relationship between angle measures and sides of a triangle and the relationships among the three sides of a triangle. The use of technology (Cabri, Jr.) allows learners to make and test conjectures as they...
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30-60-90 Right Triangles in Cabri Jr.
Young mathematicians draw and label right triangles using Cabri Jr. technology. They create other special right triangles and identify the length of the hypotenuse and each leg. Young scholars explore the ratios to determine how the...
Beyond Benign
Hit the Deck: Area and Perimeter Review
Designing a deck sure demands a lot of math. Future engineers and architects learn about the areas and perimeters of squares, rectangles, triangles, and composite figures. They apply their new knowledge to design a deck with a specified...
Curated OER
Flip's Flag
Fifth graders apply the symmetry and angle properties of polygons and use fractions to express the relationships between the areas of rectangles, squares, and triangles. They analyze various country flags and develop mathematical...
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Measuring the Area of Polygons
Fourth graders use pattern blocks to explore areas of polygons. They explain that the answers to the area of the same polygon vary according to the units of measurement used. They visualize how different units of measurement can be used...
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Does the Area of the Quadrilateral Change?
Students study area and quadrilaterals. In this multiplication and area lesson, students use Polystrip models to change rectangles to form different parallelograms. Students find the area of the models use a Geometer Sketchpad to find...
Curated OER
Review Geometry - Week 8: (Triangles)
In this triangle worksheet, learners determine the length of the sides of a triangle, perpendicular lines, and the area of triangles. This two-page worksheet contains eight problems.
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Exploring Centers of a Triangle: Part 2
Students model and solve a real-world problem by constructing the centroid of a triangle. They explore relationships of the medians of a triangle and investigate how the centroid partitions each of the medians. Students investigate...
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Areas of States - Estimation
Students estimate the area of states using the formulas for the areas of rectangles, squares, and triangles. In this geometric shapes lesson plan, students divide irregular shaped states into shapes. They use the formulas for areas of...
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Areas of Trapezoids, Rhombuses and Kites
Students calculate the area of different polygons. In this geometry lesson, students find the area for trapezoids, rhombuses and kites.
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Special Segments of Triangles Jigsaw Activity
Students identify the special segments of triangles, the median, angle bisector, altitude, and perpendicular bisectors.
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Napolean Triangle
Students investigate the Napoleon triangle theory. In this polygon lesson, students differentiate between the boundary points, interior and lattice point of a polygon. They apply concepts of equilateral triangles to solve...
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Magnetic Fields and Bermuda Triangles
Students map magnetic fields of a magnet using a compass and predict where fields cancel each other to create 'Bermuda Triangles'. In this magnetism lesson, students use a compass to map the magnetic field of a magnet. They explain how...