National Council of Teachers of Mathematics
Nctm: Illuminations: Area of Triangles
To find the area of a triangle, try to make a parallelogram using a copy of the triangle.
Khan Academy
Khan Academy: Area Challenge
Practice solving problems involving triangles, parallelograms, and composite figures. Exercises include decimals, fractions, and word problems. Area of circles is not included. Students receive immediate feedback and have the opportunity...
Quia
Ixl Learning: Area of Trapezoids
Brush up on your math skills relating to the area of trapezoids then try some practice problems to test your understanding.
Mr. Martini's Classroom
Mr. Martini's Classroom: Area of Triangles, Trapezoids & Parallelograms
Students solve for the area of rectangles, squares, triangles, trapezoids, and parallelograms.
Oswego City School District
Regents Exam Prep Center: Area of a Triangle and Parallelogram Using Trig
How can trigonometry be used to find the area of a triangle or parallelogram? Does the triangle need to be a right triangle, and how accurate can the results possibly be? The answers to these questions are found here along with several...
Homeschool Math
Homeschool Math: Area of Triangles
This lesson plan presents the idea that the area of any triangle is exactly half of a certain parallelogram -- thus we get the familiar formula of multiplying the base and the altitude and taking half of that. The lesson plan contains...
Texas Instruments
Texas Instruments: Perimeters, Areas, and Slopes Oh, My!
In this activity, students create geometric figures, and use analytic and coordinate geometry to investigate their attributes. They go through the process of proving that a quadrilateral is a parallelogram.
Math Open Reference
Math Open Reference: Area of a Rhombus
Learn about the area of a rhombus with this handy reference guide. Provides a detailed definition, formulas, and an interactive activity that enhances further explanation. Includes links to related topics.
ClassFlow
Class Flow: Perimeter & Area of Rectangles & Parallelograms
[Free Registration/Login Required] In this flipchart, students will investigate the area and perimeter of rectangles and parallelograms. This is an interactive lesson and also includes an assessment.
ClassFlow
Class Flow: Area
[Free Registration/Login Required] This creative and engaging flipchart explains the area of all kinds of shapes, to include squares, parallelograms, rectangles, triangle, and trapezoids.
George Mason University
Area Formula Lab
In this set of worksheet activities, students will be guided to discover formulas for area of polygonal shapes and circles.
Math Slice
Math Slice: Area & Perimeter: Math Worksheets
This tool allows you to create worksheets of word problems at varying levels of difficulty where students must calculate the area or perimeter of different polygon shapes. You can choose to set up the page using any of these polygon...
Learning Wave Communications
Learning Wave: Geometry, Section 2
Geometry concepts are briefly discussed at this site, including volume of a cylinder, parallelograms, circles, trapezoids, and triangles. Sample problems and applications are included for practice.
Sophia Learning
Sophia: Estimating the Area of a Circle: Lesson 4
This lesson explains how triangles and parallelograms can be used to estimate the area of a circle. It is 4 of 4 in the series titled "Estimating the Area of a Circle."
Sophia Learning
Sophia: Estimating the Area of a Circle: Lesson 3
This lesson explains how triangles and parallelograms can be used to estimate the area of a circle. It is 3 of 4 in the series titled "Estimating the Area of a Circle."
Wolfram Research
Wolfram Math World: Rhombus
This math site explains properties of the rhombus, gives a visual aid to help with the formula given for it's area.
Other
Algebra Lab: Areas and Perimeters of Triangles and Special Quadrilaterals
Learn how to find the areas and perimeters of triangles and special quadrilaterals.
Ministry of Education and Universities of the Region of Murcia (Spain)
Ministerio De Educacion Y Ciencia: Figuras Geometricas en El Plano
Interactive activities dealing with the areas of quadrilaterals figures.
Math Open Reference
Math Open Reference: Quadrilaterals
A complete reference guide to quadrilaterals including squares, rectangles, parallelograms, trapezoids, and rhombus. It provides definitions and interactive activities that enhance further explanation.
Texas A&M University
Wtamu Virtual Math Lab: Beginning Algebra: Formulas
This tutorial will show you how using formulas can help you solve problems. Include formulas for various geometric shapes and steps showing how to use them.
AAA Math
Aaa Math: Perimeter of a Rectangle
Students are taught how to calculate the perimeter of a parallelogram. Extra practice drill problems are also included.
Science and Mathematics Initiative for Learning Enhancement (SMILE)
Smile: The Area of a Circle
An investigative approach is given to exploring finding the area of a circle.
CPALMS
Cpalms: Building Graduation Caps
[Free Registration/Login Required] In this lesson plan, students build geometric models of graduation caps using stiff paper. The activity requires the application of skills in finding surface area, understanding similarity, knowing the...
Texas Instruments
Texas Instruments: Math Today Thirsty for Oil
In this activity, students can use the USA TODAY Infograph 'Thirsty for oil' to explore the area of a trapezoid and determine how to find area. Students will find the area of a parallelogram and use this to determine a formula for the...