Download Perimeter - School District 91

Shape and Space - Measurement: Perimeter
(Grade 5 outcome > Shape & Space > Measurement > C1: design & construct different rectangles given
either perimeter or area, or both (whole numbers) and draw conclusions)
Big Idea: in real life: If we want to build a fence to keep our dog inside the yard, we
need to know the distance around the yard.
Model: Perimeter is simply adding up the lengths of the sides to find the distance
around the area, any closed shaped figure. The basic unit for length is metre (m). You
will see metre with diverse prefixes e.g. kilometre (km), centimetre (cm), millimetre (ml)
(see The Metric System for units used)
See perimeter (http://www.harcourtschool.com/glossary/math2/index5.html).
Using the following website, watch how each side (length) is measured to find the
distance around (perimeter). http://www.ronblond.com/MathGlossary/
Lesson 1
Perimeter is the distance around a polygon or closed plane figure (flat figure).
Using Manipulatives: concrete exploration
a) Marching around the school, we will chant “P means perimeter, the distance around.”
b) With a partner, discuss, choose and then use different measuring units such as
nonstandard (e.g. finger) and standard (e.g. cm) to find the perimeter of the following:
a) your math notebook 1) nonstandard ___________
b) your desktop: 1) ___________
2) standard __________
2) ______________
c) four desktops together 1) ___________
2) ______________
d) the length of your arm 1) ___________
2) ______________
Class Practice: bridging the gap between concrete and abstract practice
Using mental math, we will practice find the distance around a given shape (perimeter).
http://www.amathsdictionaryforkids.com/dictionary.html
Using the following website, create different shapes using a geoboard to find perimeter.
http://nlvm.usu.edu/en/nav/frames_asid_172_g_2_t_3.html?open=activities
hint: Think of strategies for when all four sides the same?
The opposite sides are the same?
For a list of online practice sites, go to
http://www.sd91.bc.ca/frenchj/Students/Student%20Resources%20Online.html#Measurement
Shape and Space - Measurement: Perimeter
Lesson 2 Practice: Solving as a Group
We use the variable (the value changes) P to represent perimeter.
We write:
P (for perimeter) = (sum of all sides)
P = 3 cm + 2 cm + 3 cm + 2 cm (written in sequence)
P = 10 cm
We will always
1) write the formula (e.g. P = (sum of all sides)
2) rewrite the formula (equation) including all the lengths (in sequence)
* remember to include the units (e.g. cm) (**1cm = 10mm, 100 cm = 1 m)
5m
P = (sum of all sides)
4m
4m
P = 5m + 4m + 5m + 4m (note: 4 sides or 4 lengths)
5m
P = 18 m
…………………………………………………………………………..
2 cm
5 cm
4 cm
P = (sum of all sides)
P = 2 cm + 5 cm + 4 cm
P = 11 cm
…………………………………………………………………………………………………
8m
P = (sum of all sides)
4m
4m
P=
8m
P=
…………………………………………………………………………………………………
5 mm
10 mm
8 mm
P=
P=
P=
…………………………………………………………………………………………………
5m
5m
P=
5m
P=
2m
P=
P=
Lock Down What You Know: (for this activity, complete on this paper)
P=
10 cm
P=
8 cm
8 cm
P=
10 cm
P=
8 mm
12 mm
P=
P=
11 mm
9m
8m
P=
8m
P=
5m
P=
5 cm
P=
5 cm
5 cm
P=
5 cm
5 cm
P=
5 cm
3 mm
3 mm
3 mm
P=
3 mm
3 mm
3 mm
3 mm
P=
P=
3 mm
2m
2m
P=
4m
P=
3m
P=
For extra practice, go to one of the above links :
www.learnalberta.ca Grade 5 > Math > Lessons > Area and Perimeter
Shape and Space - Measurement: Perimeter
Lesson 3: Perimeter: draw a polygon shape for a given perimeter
Class Practice:
John wants to build a dog run. His dad gave him enough fencing to build a run with a
perimeter of 24 m. Draw the shape and dimensions of a run John could build. We will
share these designs.
Lock Down What You Know: You will now ‘lock down’ what you have learned.
Complete the following.
Draw a 3 – 5 sided polygon shape for each of the following perimeters.
a) P = 12 m
e.g.
3m
P = (sum of all sides)
P = 3m + 3m + 3m + 3m
3m
3m
P = 12 cm
3m
b) P = 24 cm
P=
P=
P=
c) P = 16 cm
P=
P=
P=
d) P = 32 cm
P=
P=
P=
e) P = 18 cm
P=
P=
P=
f) P = 12 mm
P=
P=
P=
Shape and Space - Measurement: Perimeter
Lesson 4: Perimeter: create different rectangles for a given perimeter
Challenge #1:
James wants to build a dog run. His dad gave him enough fencing to build a run with a
perimeter of 36 m. Draw several different rectangles (including a square) with a
perimeter of 36 m.
Challenge #2 On graph paper, or grid paper, you will draw as many different
rectangles as you can think of for the following two perimeters (the length of each
square on your graph paper will be = to 1 cm).
i)
a rectangle with a P = 48 cm
ii)
a rectangle with a P = 36 cm
(You may choose to challenge yourself and try using decimal numbers. Be sure to line
up the decimals when you add)