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Primary Mathematics: Building the Concept of AREA in Grades 4 through 7. Before we can talk about AREA we need to build the concept of Square Unit The total weight of Peter, David, and Henry is 123 kg. Peter is 15 kg heavier than David. David is 3 kg lighter than Henry. Find Henry’s weight. Peter 15kg 123 kg David Henry 3kg As we work with the BAR MODEL in grades 3 and 4 we want to emphasize the concept of UNIT. Peter UNIT David UNIT Henry UNIT 15kg 3kg PM 4A 1 Unit One SQUARE Unit 1 Unit PM 4A Find the AREA of the RECTANGLE. I count the square units covered by each rectangle to find its area A square centimeter is a unit of area. PM 4A Width = 3 cm Find the AREA of the RECTANGLE. I multiply the length and width of each rectangle to find its area Length = 4 cm The AREA of the RECTANGLE is 12 square centimeters. PM 4A 2 cm The AREA of the RECTANGLE is 8 square centimeters. 4 cm Area = 4 x 2 Area = 2 x 4 PM 4A We can use the symbols A, l, and w to represent area, length, and width. A= l x w w= 4cm l = 6cm A= 6 x 4 square cm The area of the rectangle is 24 square cm 1 inch PM 4A 1 inch One SQUARE inch PM 4A Other units of area include: meter mile foot 11yard Square meter ( m 2 ) 2 Square foot ( ft ) 111meter yard foot mile Square yard ( yd 2) 2 Square mile ( mi ) PM 4A l = 42 cm w = 34 cm A=? The area of a rectangle is 24 square inches. PM 4A If the length of the rectangle is 6 inches, find its width. ? 6 inches The width of the rectangle is 4 inches. The figure is made up of two rectangles. Find the area of the figure. PM 4A 30 feet 8 feet Area = 30 x 8 Area = 240 square feet 20 feet 12 feet Area = 240 + 240 Area= 480 square feet Area = 20 x 12 Area = 240 square feet 20 feet The figure is made up of two rectangles. Find the area of the figure. PM 4A 30 feet 8 feet Area = 10 x 8 Area = 80 square feet Area = 20 x 20 Area = 400 square feet 20 feet 10 feet Area = 80 + 400 20 feet The area of the figure is 480 square feet. PM 5A Find the area of the figure. PM 5A What is the area of the triangle? 2 cm 8 cm The area of the triangle is 8 square cm What is the area of the triangle? 2 cm 8 cm The area of the triangle is 8 square cm Area of the rectangle = 20 square units Area of one triangle = 7.5 square units Area of the second triangle = 2.5 square units Area of the original triangle = 10 square units PM 5A Find the area of the figure. Area = (2.5 + 35 + 2.5) square units Area = 40 square units Find the area of the grey region. Area of the rectangle Minus Area of the circle Find the area of the grey region.