EngageNY
Perimeter and Area of Triangles in the Cartesian Plane
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...
Shodor Education Foundation
Triangle Area
While the instructional activity 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...
Willow Tree
Area of Common Geometric Figures
Scholars can use area formulas, but can they apply what they know about area? The lesson challenges learners to think logically while practicing finding area of shapes such as rectangles, circles, parallelograms, triangles, and other...
Government of Hong Kong
Areas and Volumes - 2D Shapes
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...
Curated OER
Area of Tangram Pieces
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...
Curated OER
Investigation Area of Geometric Shapes
Fourth graders use triangle paper to design patterns using geometric figures and find the areas of those figures by counting units. Students are assessed by determining which figure has the greatest area and explaining their reasoning.
EngageNY
Using Trigonometry to Determine Area
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...
Curated OER
Finding the Area of Shapes
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...
Mathematics Assessment Project
Solving Problems with Circles and Triangles
After completing a task involving examining the ratio of areas of triangles and circles in a given figure, scholars examine sample responses to identify other strategies they could use to solve the problem.
Curated OER
Developing Formulas for Triangles and Quadrilaterals
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.
EngageNY
Real-World Area Problems
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.
Willow Tree
Surface Area of Three-Dimensional Figures
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...
Curated OER
Finding Areas of Triangles, Rectangles, and Circles
Students find the areas of geometric shapes. In this geometry lesson students find and measure the sides, perimeters, and areas of quadrilaterals, triangles, and circles. Students relate the measures to the others by using formulas.
Curated OER
Learning by Logic - Total Surface Area
Geometers calculate the area of plane surfaces using the formulas for the area of a square, rectangle, and triangle. They develop the formula for calculating the total surface area of two geometric solids: the cube and rectangular prism.
Willow Tree
Perimeter of Common Geometric Figures
Help learners understand that perimeter and circumference are one in the same. Learners apply their skills to determine the perimeter/circumference of triangles, rectangles, and circles. They then use the same strategy to find the...
EngageNY
The Scaling Principle for Area
As they investigate scaling figures and calculate the resulting areas, groups determine the area of similar figures. They continue to investigate the results when the vertical and horizontal scales are not equal.
Curated OER
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...
Texas Instruments
Identifying a Triangle by its Sides and Angles
Identify triangles by their angle measures and side lengths by looking at and measuring angle measures and side lengths. Use Cabri Jr. to construct various triangles, then manipulate the construction to create the 6 types of triangles,...
EngageNY
Properties of Area
What properties does area possess? Solidify the area properties that pupils learned in previous years. Groups investigate the five properties using four problems, which then provide the basis for a class discussion.
Curated OER
The Pythagorean Theorem and Classifying Triangles
Through the examination of the relationship between the lengths of the sides of a triangles students will learn the classification of triangles (acute, right, or obtuse).
Curated OER
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...
Alabama Learning Exchange
What You Know About the Bermuda Triangle?
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.
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...
EngageNY
Law of Cosines
Build upon the Pythagorean Theorem with the Law of Cosines. The 10th part of a 16-part series introduces the Law of Cosines. Class members use the the geometric representation of the Pythagorean Theorem to develop a proof of the Law of...