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.

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. 

When algebra and geometry get together, good things happen! Given a system of inequalities that create a quadrilateral, learners graph and find vertices. They then use the vertices and Green's Theorem to find the area and perimeter of...

Eighth graders find the circumference and diameter of several lids, show the relationship of the two measurements and derive the formula for finding the area of a circle. In this area of a circle lesson plan, 8th graders find...

Students calculate the area of different polygons. In this geometry lesson, students find the area for trapezoids, rhombuses and kites.

Students compute areas of squares, rectangles, and so on and summarize the formulas for computing areas and explain how the formulas are derived and understand the reasoning behind them.

Twelfth graders are able to deduce the area of polygons by using several methods such as coordinate method. They are able to apply the area of polygons to real life situations. Students apply the Pythagorean Theorem in problem solving...

In the first of a two-day lesson on transformations with matrix notation the class transforms the unit square using general transformations, then calculates the area of the transformed image. They discover it is the same as finding...

Students learn to derive the formula for the area of a circle. They learn to relate a circle to a parallelogram and rectangle while learning the concept of infinity as they imagine slicing an circle into infinitesimally small slices.