# Area of a Circle Lesson 2: Rounding out Area

Australian curriculum number (ACMMG197)

## Lesson abstract

The lesson consists of three stand-alone activities that, in different ways, consolidate students’ knowledge of the formula for the area of a circle.  The first activity provides pictures of circular objects in the outdoors for students to estimate the areas. The second activity enriches students’ class textbook-based practice with the circle area formula by illustrating the variation that is required for comprehensive understanding. The third activity, Precious Pendants, provides challenging multi-step area calculations and an opportunity for creativity.

## Mathematical purpose (for students)

The area of a circle can be estimated or calculated exactly using the formula, for many practical applications.

## Mathematical purpose (for teachers)

This material builds students’ skills with computation and estimations involving circle area in many variations.  Together these ideas present a comprehensive view of the use of the formula for the area of a circle. Students calculate area from the radius or diameter and vice versa. The areas of compound shapes are calculated and some complex problems are solved. Students calculate with measurements given in a range of forms – whole numbers, fractions and decimals with differing numbers of decimal places. Sensible limitations of accuracy of answers can be discussed.