Lesson Plan : Area of Circles

Teacher Name:
 Grade 6

 Finding the area of a circle.
 Subject Matter: Using pi times the radius squared to find the area of a circle. Key vocabulary: area, pi, radius, diameter, square
 The learner will select and use appropriate tools to measure two- and three-dimensional figures.
 Solve problems involving area of plane figures (circles) by finding the area of circles given the radius of the circle, or the diameter of the circle.
 Document camera, LCD projector, projector screen, white board. For each student: scissors, construction paper, graph paper, compasses.
 Review area as "a measure of the space inside a plane figure." Have students copy diagrams of a square, rectangle, triangle, and parallelogram from the projection to their graph paper and count the squares inside the figures.
 Have students draw a circle on their graph paper 6 inches in diameter. Then they cut a square from the construction paper that is radius by radius or 3 inches square. Show that this one square is not enough to fill the area. Cut another and show it is not enough. Cut a third and show that it is almost enough. Establish that a little more than three radius by radius squares will cover the area of a circle. Ask if anyone can guess what number that is a little more than three could be involved in finding the area of a circle. The answer should be pi. Establish that radius times radius times pi gives the area of a circle.
 As a class draw circles of various diameters. Under the circle write the radius x the radius x 3.14 and estimate the area using 3 for pi. Then verify by counting the squares in the circle.
 Students who may need accommodations can be paired with another student who has developed fluency in the concept and together create examples. Another accommodation could be to illustrate the concept by using play-doh to make three squares to cover a circle.
Checking For Understanding:
 Use sample questions from EOG testlets to check understanding.
 Review how pi and radius squares are involved in finding the area of circles.
 Use both EOG type questions and blank circles that students have to measure to find the radius and then the area to ensure a complete understanding.
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