Note: for full lesson w/handouts, open the attached document
In this lesson, students will derive the formula for the area of a circle by comparing it to the area of a rectangle. To do this, they will cut out slices of a circle like small pizza slices, and they will then align the slices to create a rectangle.
Circle Resource Page (NOT copied on the back of the directions) and a few extra.
3 Colors per student (markers, highlighters or pens)
Scissors (1 per student)
Glue stick or tape (1 per student)
Blank or Construction Paper (1 per student)
Pass out page 1 to each student. Ask the students for which shapes they know how to find the area? (They should respond with at least rectangle and triangle). Explain that today you need to discover the formula for the area of a circle using what you know, so you will be making a circle fit into a rectangle.
Have a student read through the steps on the front page while you model what to do on the document camera. Once you are confident the students understand the directions, pass out the circle resource page, scissors, glue or tape and a blank paper or construction paper to each student.
Make sure the students color the circumference, diameter and radii and record those colors. When students cut along the radii towards the center, encourage them to leave a small space (if they cut through, they can still tape or glue it back or you can give them another circle page).