Primary Mathematics: Building the Concept of AREAin 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 Henrys weight.PeterDavidHenry15kg3kg123 kg

PeterDavidHenry15kg3kgUNITUNITUNITAs we work with the BAR MODEL in grades 3 and 4 we want to emphasize the concept of UNIT.

1 UnitOne SQUARE UnitPM 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 areaPM 4A

Find the AREA of the RECTANGLE.I multiply the length and width of each rectangle to find its areaLength= 4 cmThe AREA of the RECTANGLE is 12 square centimeters.PM 4A

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

lWe 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 inchOne SQUARE inchPM 4A

1 mile1 yard1 foot1 meterOther units of area include:Square meter ( )Square foot ( )Square yard ( )Square mile ( )PM 4A

l = 4 feetw = 1 footA = ?l = 3 yardsw = 5 yardsA = ?l = 42 cmw = 34 cmA = ?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 feet20 feet20 feet8 feet12 feetArea = 30 x 8Area = 240 square feetArea = 20 x 12Area = 240 square feetArea = 240 + 240Area= 480 square feetPM 4A

The figure is made up of two rectangles. Find the area of the figure.30 feet20 feet20 feet8 feet10 feetArea = 20 x 20Area = 400 square feetArea = 10 x 8Area = 80 square feetThe area of the figure is 480 square feet.Area = 80 + 400PM 4A

PM 5AFind the area of the figure.

PM 5AWhat is the area of the triangle?8 cm2 cmThe area of the triangle is 8 square cm

8 cm2 cmWhat is the area of the triangle?The area of the triangle is 8 square cm

Area of the rectangle = 20 square unitsArea of one triangle = 7.5 square unitsArea of the second triangle = 2.5 square unitsArea of the original triangle = 10 square units

PM 5AFind the area of the figure.Area = (2.5 + 35 + 2.5) square unitsArea = 40 square units

Find the area of the grey region.Area of the rectangleMinusArea of the circle

Find the area of the grey region.

Because both Peters weight and Henrys weight were given relative to Davids weight, I made Davids weight the unit. *