Lesson 9
Applying Area of Circles
Lesson Narrative
In previous lessons, students estimated the area of circles on a grid and explored the relationship between the circumference and the area of a circle to see that \(A = \pi r^2\). In this lesson, students apply this formula to solve problems involving the area of circles as well as shapes made up of parts of circles (MP 1 and 2) and other shapes such as rectangles. These calculations require composition and decomposition recalling work from grade 6.
Also, in this lesson students are introduced to the idea of expressing exact answers in terms of \(\pi\).
Learning Goals
Teacher Facing
- Calculate the area of a shape that includes circular or semi-circular parts, and explain (orally and in writing) the solution method.
- Comprehend and generate expressions in terms of $\pi$ to express exact measurements related to a circle.
Student Facing
Let’s find the areas of shapes made up of circles.
Required Materials
Required Preparation
It is recommended that four-function calculators be made available to take the focus off computation.
Learning Targets
Student Facing
- I can calculate the area of more complicated shapes that include fractions of circles.
- I can write exact answers in terms of $\pi$.
CCSS Standards
Addressing
Print Formatted Materials
Teachers with a valid work email address can click here to register or sign in for free access to Cool Down, Teacher Guide, and PowerPoint materials.
| Student Task Statements | docx | |
| Cumulative Practice Problem Set | docx | |
| Cool Down | Log In | |
| Teacher Guide | Log In | |
| Teacher Presentation Materials | docx |