![]() Students will likely suggest that the shape is unfamiliar. (This can be done if students cut only along the bold, solid, black lines.) Then, have students arrange the shapes so that the points of the wedges alternately point up and down, as shown below:ĭifferent parts of the circle ( radius and circumference) should be highlighted in a color from the Introductory Activity. In pairs or small student groups, have students cut the circle from the sheet and divide it into four wedges. It might be useful to use the jigsaw cooperative learning structure (group members disperse to other groups) to share methods for finding area across groups. After students have estimated the area of several objects using multiple methods, have students share their methods for calculating area in small groups or as a whole class.(You may need to provide a sample drawing of this method, like the one shown below.) Students could determine the area of the inscribed and circumscribed shapes to get lower and upper estimates, respectively. Then, the same shape could be inscribed within the circle. Students can inscribe the circle in a square, hexagon, or some other polygon. ![]() For a connection to mathematical history, you may want to include a brief overview of Archimedes and his method for calculating the area of a circle.) (This method is similar to a method used by Archimedes, and it is the method that will be used later in this lesson. They can approximate the area of each wedge using the triangle formula. Students can divide the circle into wedges by drawing radii.Students can trace the shape of their object on a piece of centimeter grid paper and count how many square centimeters make up the total area of the circle.Students may use any method they like to estimate the area of their objects. Students would be able to trace the circles using pencils or dry erase markers and approximate the area of each circle by counting the number of squares. Cut out circles of various sizes and give a set to each small group of students along with centimeter grid paper or centimeter grid paper transparency. Strategy for differentiation: Another method would be to have students estimate the area of circles using centimeter grid transparencies and cut out circles. Note: The other two columns will be completed later in the lesson. Their estimate for the area of the object.Working in small groups and using the Area of Circles Activity Sheet (download from Materials section), students should individually complete the first two columns: Give students an opportunity to estimate the area of the circular objects that they have brought to class. If necessary, give some students a word bank with the vocabulary: circumference, diameter, and radius and discuss parts of a circle with students. ![]() Monitor student progress to check for any misconceptions. Students should be able to calculate radius from diameter and diameter from radius. In particular, students should realize that d = 2r. Be sure students are identifying the radius and the diameter. Have students highlight each part of a circle they know and recognize using a different color.
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