Calculating Area - A Primer

by Deb Russell
Deb Russell is a school principal who has taught mathematics at all levels. She is also a freelance writer with more than 14 years of experience.
Updated March 17, 2017

Understanding how to calculate area is important to understand at the early age of 8-10. Calculating area is a pre-algebra skill that should be well understood prior to beginning algebra. Students by grade 4 need to understand the early concepts of calculating the area of a variety of shapes.

Formulas for calculating area use letters which are identified below. For example the formula for the area of a circle will look like this:

A = π r 2 

This formula means that the area is equal to 3.14 times the radius squared.

The area of a rectangle would look like this:

A = lw

This formula means that the area of the rectangle is equal to the length times the width.

Area of a triangle -  

A= ( b x h ) / 2.  .( See Image 1).

To best understand the area of a triangle,  consider the fact that a triangle forms 1/2 of a rectangle. To determine the area of a rectangle , we use  length times width ( l x w ).  We use the terms base and height for a triangle, but the concept is the same. (See Image 2 ). 

Area of Sphere -  ( the surface area )  The formula is 4 π r 2  

For a 3-D object the 3-D area is termed as the volume.

Area calculations are used in many sciences and studies and have practical daily uses such as determining the amount of paint required to paint a room. Recognizing the various shapes that are involved is essential to calculating area for complex shapes. 
 

(See images)