Illustrative Mathematics
Illustrative Mathematics: G Gpe Triangle Perimeters
Students are shown two triangles touching points on a coordinate grid and are asked to answer questions about their perimeters. The purpose of this task is to apply the Pythagorean theorem to calculate distances and areas. Aligns with...
Math Open Reference
Math Open Reference: Triangles
A complete reference guide to types of triangles and triangle perimeter and area. It provides definitions and interactive animated activities that enhance further explanation.
Homeschool Math
Homeschool Math: Area of Parallelograms
This instructional activity presents the idea that the area of any right triangle is exactly half of a certain rectangle, and contains varied exercises for students.
Math Is Fun
Math Is Fun: Area of Triangles Without Right Angles
Learn how to find the area of triangles without right angles. Find the formula to use depending on the information you know about the triangle: base and height, three sides, or two sides and an angle.
Khan Academy
Khan Academy: Area of Triangles
Practice finding the area of right, acute, and obtuse triangles. Students receive immediate feedback and have the opportunity to try questions repeatedly, watch a video or receive hints.
Illustrative Mathematics
Illustrative Mathematics: 6.g Same Base and Height, Variation 1
Make the following triangles on a geoboard. Remember that the pegs are equally spaced in a square grid. Compare the areas of the triangles. Aligns with 6.G.A.1.
Illustrative Mathematics
Illustrative Mathematics: 6.g Base and Height
The purpose of this task is to help students understand what is meant by a base and its corresponding height in a triangle and to be able to correctly identify all three base-height pairs. Aligns with 6.G.A.1.
Sophia Learning
Sophia: Using Triangles to Find the Sum of Interior Angles: Lesson 1
This lesson demonstrates how to use triangles to determine the sum of the interior angles of a polygon. It is 1 of 5 in the series titled "Using Triangles to Find the Sum of Interior Angles."
Houghton Mifflin Harcourt
Holt, Rinehart and Winston: Homework Help: Perimeter and Area of Triangles and Trapezoids
Get independent practice working with finding the perimeter and area of triangles and trapezoids. Each incorrect response gets a text box explanation and another try. Correct responses are confirmed.
Cool Math
Coolmath: Precalculus Basic Formulas to Know
This CoolMath resource provides an introduction to some Precalculus formulas.
Alabama Learning Exchange
Alex: Function Machine
During this lesson plan, eighth grade students will interpret the perimeter of a train of triangles, squares, trapezoids, or hexagons as a function (for each input, there will be exactly one output). Students will represent their data in...
Better Lesson
Better Lesson: Finding the Area Review and Assessment
Sixth graders find the area of rectangles, triangles, parallelograms, and trapezoids by using formulas or by composing into rectangles or triangles.
Illustrative Mathematics
Illustrative Mathematics: 8.g Circle Sandwich
Eighth graders are presented with a drawing of a large square inscribed by a circle which is itself inscribed by a second square. They are asked to find the area of the circle outside the smaller square and compare it to the area of the...
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.
National Institute of Educational Technologies and Teacher Training (Spain)
Ministerio De Educacion: Veintiocho Cerillas
Remove four matches to the center of the square then repositions the other matches in such a way that the sum of them on each side is 11.
Texas Instruments
Texas Instruments: Measuring Polygons an Introduction to Cabri Jr.
This activity is designed as an introduction to using the Carbri Jr. application on the TI-83+/84+ calculators. Students are guided through the menu system and are shown how to draw triangles, quadrilaterals and and a pentagon. Perimeter...
Varsity Tutors
Varsity Tutors: Hotmath: Graphing Calculator Practice Problems Geometry
Practice using your graphing calculator for Geometry problems. If you get stumped or if you would like to check your work, then select the View Solution button, which is located directly under each problem.
That Quiz
That Quiz: Triangulos
These interactive activities are designed to examine the mathematical concepts of length, perimeter, and area. These activities may be used to develop students' understanding of these mathematical concepts.
Calculator Soup
Calculator Soup: Regular Polygon Calculator
Use this calculator to calculate properties of a regular polygon. Enter any 1 variable plus the number of sides or the polygon name. Calculates side length, inradius, circumradius, area, and perimeter.
Vernet -Virtual Education Resources Network
Salon Hogar: Referencia Rapida De Formulas Geometricas
This site provides the user with a useful reference to different geometric forms, their elements, formulas, and areas. Entirely in Spanish.
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...
Better Lesson
Better Lesson: Remarkable Rectangles
Rectangle is SO MUCH like triangle! Those darned angles--they'll get beginning learners! This is a fun way to practice rectangle!
New Advent
Catholic Encyclopedia: Alcuin
This Catholic Encyclopedia site offers a very good biography of Alcuin, with extensive information on his work as an educator, a scholar, a theologian, and a liturgist of the 8th century. Please note that "The Catholic Encyclopedia" is a...