Curated OER
Investigating Area Relationships
Learners investigate the area of various figures. They construct triangles and quadrilaterals using Cabri Jr. and discuss the relationships between different angles, side lengths, and figures.
EngageNY
Ptolemy's Theorem
Everyone's heard of Pythagoras, but who's Ptolemy? Learners test Ptolemy's Theorem using a specific cyclic quadrilateral and a ruler in the 22nd installment of a 23-part module. They then work through a proof of the theorem.
Curated OER
Angle Bisectors and Medians of Quadrilaterals
Young scholars investigate the properties of quadrilaterals formed by angle bisectors of a given quadrilateral and quadrilaterals formed by the medians of quadrilaterals. This Cabri Jr. lesson provides opportunity for conjecture and...
Illustrative Mathematics
What is a Trapezoid? (Part 1)
Challenge your class to construct a definition for trapezoids. Looking at four examples and four non-examples, students individually create definitions and use them to classify an unknown shape. Allow for small group and whole-class...
Mathematics Assessment Project
Evaluating Statements About Length and Area
Class members complete an assessment task by identifying whether statements about triangles and quadrilaterals are always true, sometimes true, or never true. They then participate in a sorting activity with the same objective.
Curated OER
Inscribed Quadrilaterals and Parallelograms
Learners differentiate between inscribed quadrilaterals and parallelograms. In this geometry lesson, students identify the shaped of the polygons when it is inscribed inside of a circle. They calculate the missing angles of the inscribed...
Curated OER
Geometry: Classifying Quadrilaterals
Students use construction technology to identify and find relationships between the attributes of various quadrilaterals. They make and test conjectures about the distinguishing properties of parallelograms, rectangles, rhombuses,...
Curated OER
Creating a Midpoint Quad
Using a TI Navigator to drag quadrilaterals around to create different shapes, young scholars learn how to draw midpoints in their quadrilaterals. In this geometry lesson plan, students solve problems using the properties of...
Curated OER
Diagonals to Quadrilaterals II
Pupils identify the properties of different polygons. In this geometry lesson, students find the slope of a line and calculate the distance between two lines. They differentiate between similar and congruent polygons.
Curated OER
Properties of Parallelograms
High schoolers discover properties of parallelograms as they construct a parallelogram using Cabri Jr. They will measure angles and side lengths of their construction and determine the relationship between the diagonals of a...
Curated OER
Geometry is Fun and EverywhereGeometry, You Don’t Care? Geometry is Fun and Everywhere
Third graders investigate shapes in our world. In this geometry instructional activity, 3rd graders describe plane and solid shapes and identify angles, solid objects and lines of symmetry. Students use online resources, graphic...
Curated OER
Rectangles and Parallelograms
Students compare parallelograms and rectangles. In this comparing parallelograms and rectangles lesson, students make a chart to compare parallelograms and rectangles. Students are given set of quadrilaterals and they must classify...
EngageNY
Perimeter and Area of Polygonal Regions Defined by Systems of Inequalities
When algebra and geometry get together, good things happen! Given a system of inequalities that create a quadrilateral, learners graph and find vertices. They then use the vertices and Green's Theorem to find the area and perimeter of...
Illustrative Mathematics
Sum of Angles in a Polygon
How can learners use algebra to solve a geometry problem? Help learners create an equation that shows the relationship between the number of sides of a polygon and the sum of the interior angles. Students are asked to divide the...
Curated OER
Identify Polygons: Algebra/Geometry Institute
Eighth graders classify geometric figures. In this polygon lesson, 8th graders identify given geometric figures. They compare and contrast different polygons. Students name line segments, identify parallel lines, and interesections. ...
Curated OER
IGD: Perpendicular Bisector
Students draw perpendicular bisectors. In this perpendicular bisectors lesson, students identify the perpendicular bisector in a polygon. They use web tools to create and measure perpendicular bisectors. Students identify lines of...
Illustrative Mathematics
What is a Trapezoid? (Part 2)
This collaborative activity investigates the meaning of a trapezoid and a parallelogram. It begins by presenting two different definitions of a trapezoid. Learners are to reason abstractly the difference between the two definitions and...
Noyce Foundation
Lyle's Triangles
Try five problems on triangles. Levels A and B focus on shapes that can be created from right triangles. Level C touches upon the relationship between the area of a six-pointed star and the area of each triangle of which it is composed....
101 Questions
Best Reflection
Which is the best reflection of them all? Given four diagrams, pupils determine which one shows the most accurate reflection of a quadrilateral. Two images provide the distances of each vertex from the line of reflection, as well as the...
Illustrative Mathematics
Is This a Parallelogram?
If both pairs of opposite sides of a quadrilateral are congruent, is the quadrilateral a parallelogram? This task asks learners to determine the answer and to support their answer with a proof. The resource includes a commentary for...
Curated OER
The Trapping of Trapezoids
This is a nice hands-on activity where young geometers create trapezoids and calculate their area by looking at areas of quadrilaterals and triangles.
Curated OER
Areas of Polygons
Young mathematicians calculate the area of polygons in this algebra lesson plan. They find the determinant as they calculate the areas for triangles and quadrilaterals. They also use scalar multiplication to find the determinant.
Texas Instruments
The Determinant of a Matrix
Students calculate the determinant. For this algebra lesson, students find the determinant and use to calculate the area of a triangle. They calculate the area of a quadrilateral in a plane.
Curated OER
Measurement: Finding Areas of Rectangles
Gardening geometers construct the formula for the area of a rectangle by viewing a video revolving around two young people, their lawn mowing business, and their need to charge by the square meter. A relevant real-life application lesson!
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