OBJECTIVES: To calculate the area and perimeter of simple compound shapes that can be split into rectangles. UNIT: 4
To compare perimeters and areas of different shapes.
LESSON: 5 FOCUS: PERIMETERS AND AREAS
LANGUAGE OF LEARNING LANGUAGE FOR LEARNING LANGUAGE THROUGH
; Vocabulary of the topic ; Language that comes ; Language instruction
Give children worksheet 4.8 an ask what is the perimeter and area of simple through the lesson
Parallelogram compound shapes that can be split into rectangles.
Hexagon Ask children to write down the perimeter and the area of shape A on the Factor whiteboard.
Area Collect responses and ensure that the correct units are used: cm and cm2.
Perimeter Remind children that the area of a rectangle is “length x breadth”.
Square centimetre Repeat for shapes B and C. Establish that all three shapes have the same area, Equilateral triangle but different perimeters.
Ask children to name shapes D and E and to find their areas. Draw attention to
the fact that shape D is half of shape B and drawing a rectangle around the
triangle is a useful strategy.
Collect responses and discuss children’s strategy for finding the area of shape
Ask what the names of shapes F and G are
Collect responses and check spelling of these words.
Ask what strategy we can use to find their areas.
Discuss the children’s responses and ask them to find the areas. Collect answers
and correct errors.
Ask what rectangle could we draw that would have same area as shape F and
what rectangle would have the same area as shape G.
Collect answers and identify that finding the factors of two areas of the shapes
will give the rectangles.
On the board, draw an L- shape. Ask what information we need to find the area
and perimeter of the shape.
Once this has been established add some dimensions, in cm, to the L-shape. Ask what its perimeter and its area are.
Agree with the perimeter and show that the area can be found by dividing into
rectangles and adding or by drawing a large outer rectangle and subtracting.
Ask what L-shape they can draw that has an area of 36 cm2.
Discuss how to do this and demonstrate on the board. Find its perimeter and
Children work in pairs to find different L-shapes with area 36 cm2 and record
the perimeters. Give out centimeter squared paper.
Ask what the L-shape with the longest perimeter is and what L-shape has the shortest perimeter.
Discuss their answers and correct any errors or misunderstandings.
Give out worksheet 4.9 and 4.10.
Discuss the results.
Give out 4.11 for homework.
; Questions for learning ; Possible answers
What is the perimeter and area of It is…………cm2.
What are the names of shapes F and G? (name of a polygon).
What strategy can we use to find their Maybe drawing rectangles/counting
What rectangle could we draw that A rectangle with the same length. would have same area as shape F?
What rectangle would have the same We could cut it and check it.
area as shape G?
What information do we need to find the We need the measure of the long area and perimeter of this shape? length, the short length and the
What is its perimeter? It is……..
What is its area? It is……..
What L-shape can you draw that has an We need the measure of two lengths
area of 36 cm2? and two breadths.
What is the L-shape with the longest
perimeter? That/This one.
What L-shape has the shortest perimeter?
; Language to express conclusions
“The area of irregular shapes can be found by dividing the shape into rectangles
and adding or by drawing a large outer rectangle and subtracting” RESOURCES: Whiteboards, centimetre squared paper, worksheets 4.8, 4.9, 4.10 and 4.11, P.Point area and perimeter U4 L5,