Texas Instruments
Texas Instruments: Heron's Formula
This activity allows students to find the area of a triangle using Heron's formula.
Texas Instruments
Texas Instruments: Investigating Properties of Trapezoids
Students draw trapezoids and investigate their properties. They derive the area formula for a triangle from the area formula for a trapezoid. They also investigate the terms: Isosceles trapezoid and Tessellation. Numerous supplementary...
Wolfram Research
Wolfram Math World: Midpoint
This MathWorld site offers a lesson on finding the midpoint of a line segment using a compass and finding the midpoint of the sides of a triangle. This site also has an interesting way of drawing two triangle with equal area by finding...
OER Commons
Oer Commons: Polygons
Seventh graders find the area of regular polygons, recalling what they already know about the area of geometric shapes and generalizing a formula for any regular polygon.
Purple Math
Purplemath: Geometry Word Problems: Introduction
Introduces how to set up and solve simple geometric-figure word problems. Includes advice regarding formulas to memorize.