# Primary Mathematics: Building the Concept of AREA in Grades 4 through 7.

## Presentation on theme: "Primary Mathematics: Building the Concept of AREA in Grades 4 through 7."— Presentation transcript:

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 David Henry 15kg 3kg 123 kg

Peter David Henry 15kg 3kg UNIT As we work with the BAR MODEL in grades 3 and 4 we want to emphasize the concept of UNIT.

1 Unit One SQUARE Unit PM 4A

Find the AREA of the RECTANGLE. A square centimeter is a unit of area. I count the square units covered by each rectangle to find its area PM 4A

Find the AREA of the RECTANGLE. I multiply the length and width of each rectangle to find its area Length Width = 4 cm = 3 cm The AREA of the RECTANGLE is 12 square centimeters. PM 4A

4 cm 2 cm Area = 4 x 2 Area = 2 x 4 The AREA of the RECTANGLE is 8 square centimeters. PM 4A

l We can use the symbols A, l, and w to represent area, length, and width. w = 6cm = 4cm A= l x w A= 6 x 4 square cm The area of the rectangle is 24 square cm PM 4A

1 inch One SQUARE inch PM 4A

1 meter 1 mile 1 foot 1 yard 1 foot1 meter Other units of area include: Square meter ( ) Square foot ( ) Square yard ( ) Square mile ( ) PM 4A

l = 4 feet w = 1 foot A = ? l = 3 yards w = 5 yards A = ? l = 42 cm w = 34 cm A = ? PM 4A

The area of a rectangle is 24 square inches. If the length of the rectangle is 6 inches, find its width. 6 inches ? The width of the rectangle is 4 inches. PM 4A

The figure is made up of two rectangles. Find the area of the figure. 30 feet 20 feet 8 feet 12 feet Area = 30 x 8 Area = 240 square feet Area = 20 x 12 Area = 240 square feet Area = 240 + 240 Area= 480 square feet PM 4A

The figure is made up of two rectangles. Find the area of the figure. 30 feet 20 feet 8 feet 10 feet Area = 20 x 20 Area = 400 square feet Area = 10 x 8 Area = 80 square feet The area of the figure is 480 square feet. Area = 80 + 400 PM 4A

PM 5A Find the area of the figure.

PM 5A What is the area of the triangle? 8 cm 2 cm The area of the triangle is 8 square cm

8 cm 2 cm What is the area of the triangle? 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 rectangleMinusArea of the circle

Find the area of the grey region.