National Council of Teachers of Mathematics
The Math Forum: Problems Library Geometry Triangles
This site contains a wealth of problems that deal with the basic definitions of medians, altitudes, angle bisectors, and perpendicular bisectors or the defining characteristics of the different types of triangles. There are also...
CK-12 Foundation
Ck 12: Geometry: Triangles and Quadrilaterals Study Guide
[Free Registration/Login may be required to access all resource tools.] This study guide reviews the formulas for area and perimeter of triangles and different kinds of quadrilaterals.
Annenberg Foundation
Annenberg Learner: Constructing Triangles
Use a "linkage strip" to build triangles with different side lengths. When you build a triangle, see if you can deform it into a different triangle while keeping the side lengths the same.
Illustrative Mathematics
Illustrative Mathematics: G Srt Similar Quadrilaterals
The goal of this task is to study if the analog of the AA criterion for similarity of triangles holds for different types of quadrilaterals. Aligns with HSG-SRT.A.2.
OER Commons
Oer Commons: Exploring the Properties of a Triangle
For this lesson, middle schoolers explore properties of triangles. They fold paper to make a triangle and measure its angles. Students also draw triangles with given conditions. Included are examples, discussion questions, and closing...
Sophia Learning
Sophia: Using Triangles to Examine Quadrilaterals: Lesson 5
This lesson demonstrates how to determine properties of quadrilaterals by using triangles. It is 5 of 5 in the series titled "Using Triangles to Examine Quadrilaterals."
Cuemath
Cuemath: Equilateral
Learn all about the basic properties of equilateral. This lesson targets the meaning of equilateral, shows how to construct equilateral shapes, explores some of the equilateral shapes and properties, and how to apply them while solving...
Other
Algebra Lab: Areas and Perimeters of Triangles and Special Quadrilaterals
Learn how to find the areas and perimeters of triangles and special quadrilaterals.
CK-12 Foundation
Ck 12: Interactive Geometry: 1.6 Area or Perimeter of Triangles/ Quadrilaterals
Explore finding and measuring perimeter of figures.
Illustrative Mathematics
Illustrative Mathematics: G Srt Extensions, Bisections, Dissections in Rectangle
In this task, learners must draw a diagram from a verbal description and use their understanding of similar triangles to find the area of a quadrilateral. Aligns with G-SRT.B.5.
Texas Instruments
Texas Instruments: Investigating Area Relationships
The interactive Cabri Jr. geometry application makes it easy to measure the area of triangles and quadrilaterals. In this activity, students will explore some interesting area relationships in quadrilaterals.
Mangahigh
Mangahigh: Pyramid Panic: Basic Shapes to Advanced Geometry
Guide a mummy safely through the burial chambers of a pyramid as you solve length and area problems in basic to advanced geometry. There are four game zones that deal with circles and triangles, quadrilaterals, the Pythagorean Theorem,...
Science Struck
Science Struck: Similarity Statement in Geometry With Examples
Models how to write a similarity statement about different types of triangles and quadrilaterals.
Government of Alberta
Learn Alberta: Math Interactives: Exploring Shape Classification
Investigate the properties of triangles, quadrilaterals, and regular polygons using this interactive Learn Alberta math resource. Students are able to practice classifying shapes based on their different properties. Be sure to follow the...
Ministerio de Educacion, Cultura y Deporte (Spain)
Cnice: Relacion De Ejercicios Interactivos.
In Spanish. Interactive activities online on various geometric and trigonometric concepts such as area, perimeter, secants, tangents, etc. A terrific resource for students. Site is organized acoording to shape. (triangle, quadrilaterals,...
Math Drills
Math Drills: Geometry Worksheets
Download these worksheets to sharpen your geometry skills. Sheets focus on angles, coordinate geometry, triangles, quadrilaterals, transformations, and three-dimensional geometry, and more.
ClassFlow
Class Flow: Area of Polygons
[Free Registration/Login Required] This flipchart provides students with notes and practice with using formulas for finding the area of triangles and quadrilaterals.
Texas Instruments
Texas Instruments: Tessellations and Tile Patterns
Students understand that a tessellation is covering of a plane with a pattern of figures so there are no overlaps or gaps. They draw quadrilaterals and triangles and explore monohedral, dihedral, and trihedral tessellating patterns.
Homeschool Math
Homeschool Math: Basic Shapes
This review lesson about basic shapes (polygons)contains varied hands-on exercises and tilings about triangles, quadrilaterals, pentagons, and hexagons.
BBC
Bbc: Bitesize: Maths: 2 D Shapes
Learn about the properties of 2-D shapes: circles, triangles, polygons, and quadrilaterals. Includes information, video, and examples about each, with games and quizzes for reinforcement.
Khan Academy
Khan Academy: Use Pythagorean Theorem to Find Area and Perimeter
Find the area and perimeter of triangles and quadrilaterals by first using the Pythagorean Theorem to find missing side lengths. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video, or...
Alabama Learning Exchange
Alex: Have Your Math and Eat It, Too!
In this two-day lesson plan, students will collaborate to create a healthy pizza using only geometric items that have been precisely measured. Students must identify the items as triangle, quadrilateral (parallelogram), or cube. Next,...
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.
BBC
Bbc: Area in General
You can pick up some valuable pointers on how to find the area of a triangle, rectangle, and other quadrilaterals. When you finish working your way through the pages you can take an on-line "Test Bite," and check your understanding.