Foundations Sampler 2024

43 Exploring Area Lesson Plans 46 ©MathTeachersPress, Inc. Reproduction by anymeans is strictly prohibited. 46 Find the area of each rectangle or square.Use the above formulas. Area of a Square or Rectangle with a Formula You can find the area of a square or a rectangle by following a pattern or formula. A formula is an equation with at least two variables. a rectangle a square area pattern:multiply _____ _____ area pattern:multiply _____ _____ Formula: A = length width A = lw A = 4 3 = 12 sq.units or 12 units 2 Formula: A = side side A = s s or s 2 A = 3 3 = 9 sq.units or 9 units 2 Use your centimeter ruler to find the area of each figure. 1. A = lw = ______ ______ = ______sq.units 2. A = s s = ______ ______ = ______sq.units 3. A = = ______ ______ = ______sq.units 4. A = ________________ = ______ ______ = ________cm 2 5. A = ________________ = ______ ______ = ________cm 2 Use your centimeter ruler to help answer the question. Which shape has an area of 2 square centimeters? A B C D 6. A = ________________ = ______ ______ = ________cm 2 3 2 6 4 4 16 5 3 15 lw lw lw 4 3 12 2 2 4 5 2 10 S 2 side length width side Objective: To find the area of rectangles or squares using a pattern or formula. Materials: Strips of transparent centimeter graph paper, 1 cm 2 cm, 1 cm 3 cm, 1 cm 4 cm, and 1 cm 5 cm, Area Tic-Tac-Toe (Master 21) Vocabulary: formula, variable Looking for a Pattern Display a colored transparency of a rectangle, 3 cm 5 cm. How can we find the area of this figure? Review the meaning of area as covering the surface with square units. Demonstrate two different ways of finding the area with manipulatives. 1. Cover the rectangle with 15 one-centimeter squares. 2. Cover the rectangle with 3 rows of 1 cm 5 cm strips. How many squares in each strip or row? (5) How many rows? (3) How many squares in all? (15) What is the pattern for finding the area of a rectangle? (Multiply the numbers of rows by the number of squares in each row or multiply one side time the other or multiply length times width.) Write on the board: Area = number in each row number of rows Area = length width We can express this in a formula where we use the first letter of each word to stand for the words. These letters are called variables. A variable is a symbol used to represent an unknown number or numbers. A formula is an equation with at least two variables. Write on the board: A = lw = 5 • 3 = 15 sq. units Repeat the activity with a colored transparency of a 3 cm 3 cm cut-out square. Place three 1 cm 3 cm strips on the figure. Write on the board: Area = number of squares in each row times number of rows Area = s • s = s 2 Read the information together at the top of the page. Be sure to carefully explain how the pattern, area = length width becomes the formula A = lw . Work problems 1 and 5 together. Have students complete the page on their own. Area Tic-Tac-Toe (Master 21) Skill Builders 38-6 Sample of Scripting (Bold Type) IM3 Lesson Plan Students use centimeter squares and strips to find the area of a polygon. p How many squares in each strip or row? (5) How many rows? (3) How many squares in all? (15) What is the pattern for finding the area of a rectangle? (Multiply the numbers of rows by the number of squares in each row or multiply one side time the other or multiply length times width.)