# Measurement of Perimeter and Area

## Measurement of Perimeter and Area

Lesson Planning of Measurement of Perimeter and Area

Subject Mathematics

Students` Learning Outcomes

• Identify the units for measurement of perimeter and area.
• Write the formulas for perimeter and area of square and rectangle.
• Apply formulas for perimeter and area of a square and rectangle.

Information for Teachers

• Any enclosed shape which doesn’t` have any open ends and it starts and ends at the same point is called closed shape.
• Shapes whose line segments don`t meet and it don`t start and end at the same point is called open ended shape.

• Distance of around the closed ended shape is called its perimeter.
• Perimeter can be measured in the units of meter, centimeter and kilometre.

• Perimeter of a shape is calculated by adding length of all of its sides.
• Area is the amount of region that a shape covers i.e. Area = Length x Breadth
• Area can be measured in square units.

Material / Resources

Writing board, chalk / marker, duster, pencil, paper, scissors, text paper, ruler, chart paper cutouts with different shapes and size etc.

Introduction

• Ask the students:
1. What is an open ended and closed ended shape?
2. What is perimeter?
3. What is area?
4. How can we measure “perimeter” and “area”?
• Discuss with the students that a perimeter and an area can be measured in m, cm, km, etc. area is measured in square units.

• Ask students to walk in the ground and identify the perimeter and an area of a ground.
• Ask students to identify and point to the perimeter and area of their pencil box, teacher`s desk, and any note book.

Development

Activity 1

• Draw the following shape on the board.
• Ask them to find out the perimeter of the shape. (Let them think and then check their answers).
• Perimeter can be measured bt adding lengths of a shape.
• Therefore the perimeter of the rectangle is 7 + 3 + 7 + 3 = 20 units.
• Ask them to draw different size shapes to find perimeters.
• Divide class into group of four members.
• Give each group drawings of different shapes of different sizes.

• Ask them to mention the name of shapes and find their perimeters.
• Appreciate for correct answers.
• Correct the wrong answers.
• Make it clear that a perimeter is found by adding length of all the sides.

Activity 2

• Draw a rectangle like shape as shown on the board.
• Tell them how we will find the length of the other 2 sides.
• In a rectangle opposite sides are equal, so to work out the perimeter of a rectangle you just need to know only the length and width.
• Look at the shape and find the length of each side. Add the lengths:
• Total length of all sides is 05 + 12 + 05 + 12 = 34 NOW find the units.
• The lengths have been measured in centimetres, so the perimeter will also be measured in centimetres.
• The perimeter will be 34 centimetres.

Activity 3

• Ask the students:
• What could be the easiest way to find the perimeter of a rectangle? Help them in concluding that since the 2 opposite sides of a rectangle are equal so if we add the length and breadth and multiply the sum by 2 then we can get perimeter.

• Formula for perimeter can also be written as:
• Perimeter of a rectangle = 2 x (l + b) = 2 x 3 + 5= 16
• Where L = length and B = breadth
• Ask them to apply the formula to different rectangular shapes and verify by adding all 4 sides.
• Ask what is the perimeter of a square having side –length 74 cm?  Help them to conclude that:

• Since a square has 4 sides of equal length, the perimeter of the square is 4 + 4 + 4 + 4 = 16.Or 4 x 4 = 16.

1. What could be the easiest way to find out the perimeter of a square?
• Help them to conclude that since all 4 sides of a square are equal we can find out its perimeter by multiplying one side of the square by 4.
• So, perimeter of a square = 4 x L
• Where L = length of a side of a square.
• In above example Area = 4 x 4 =  16 cm
• Draw a square and rectangle on the board.
• Ask them to look at the shapes:
1. How many squares is each divided into (4 and 12)
• If the side of each smaller square is 1 cm how much is the area of the square?  4 cm 2 (because it has 4 small 1 cm squares)
1. What will be the area of the rectangle? 12 cm 2(because it has 12 small 1 cm squares)

Activity 5

• Ask them to find out the area of the rectangle.
• Tell them the formula for area of rectangle.

• The formula is:
• Area = L x B
• Whereas L= length and B = breadth so, we know that
• L = 5
• B = 3, so, Area = 5 x 3 = 15
• Note: the area of a figure measures the size of the region enclosed by the figure. This is usually expressed in terms of some square unit.
• A few examples of the units used are square meters, square centimetres, square inches, or square kilometres.
• The area of a rectangle is composed of its “width” and “length”. Explain few more examples to the students to make them understand about the concepts.

Area of a Rectangle:

Example 1

1. What is the area of a rectangle having a length of 6 cm and a width of 2 cm?
• The area is the product of these two sides –lengths, which is 6 x 2 = 12 cm 2.

Teacher`s Role

1. What is the area of a square having side- length 4 cm? The area is the square of the side-length, which is 4 x 4 = 16 cm 2or (4)2 = 16 cm 2.
• Explain how to find area of a square?

Example 2

• As the students to find the area of a squares in a grid
• Area can be found by counting squares in the grid.
• Total small squares inside the shape are 100. Area of a square is 100 square units.

Example 3

• Draw different grids and ask students to come and tell the units of a shape by counting squares in the grid.

Sum up / Conclusion

• Distance of around the closed ended shape is called its perimeters.
• Perimeter of a shape is calculated by adding length of all of its sides.
• Area is the amount of region that a shape covers i.e. Area = Length x Breadth
• Area can be measured in square units.

PERIMETER VS AREA

 Area Perimeter Definition: Area is the space or region occupied by a closed figure. Perimeter is the distance around a closed figure. Measurement: Square unit. Measures two dimensions e.g. 24 in2 or 24 inches squared. Measures one dimensions e.g. 24 in. or 24 inches Usage: For example to carpet the whole room. For example to put a fence around the garden. Square: s2, where s is the length of one side of the square. 4s, where s is the length of one side of the square. Rectangle: L w, where L and w are the length and width of the rectangle. 2 L + 2 w, where L and w are the length and width of the rectangle.

Formulas to calculate perimeter and area

 Shape Formula for perimeter Formula for Area Variables Square 4L L2 Where L is the side length Rectangle 2 L + 2w L w Where L is the length and w is the width

Assessment

Individual work:

• Assign questions from the textbook to be done individually and record for assessment and follow up.
• Write the following on the board and ask students to solve.
• A rectangle has sides equal to 2 cm and 7 cm find out its area and perimeter using formula.
• A square has one side equal to 8 cm so; find out its area and perimeter using formulas.s
• Involve the students in solving the problems given in the end of the lesson of textbook