Lesson Plan – Lesson 4 Circumference
Objectives and Habits of Mind
•To accurately measure using a tape measure (Level 3)
•To estimate the Circumference of a circle by multiplying the diameter by 3 (Level 4)
•To estimate the Circumference of a circle by multiplying the diameter by Pi(Level 5)
•To calculate the radius, diameter or circumference of circles and semi circles when given one other
measurement. (Level 6)
•I can work well in a group, listening attentively and taking on different roles when needed.
•I can negotiate and follow ground rules, to ensure fairness and cooperation when working with others.
Keywords
Radius, Circumference, Diameter, Pi
Mental and Oral Starter
Pupils to use the mini white boards to round numbers to one decimal place.
Main Activity
Pupils to work in groups to measure the diameter and circumference of tins to discoverer the
relationship between the diameter of a circle and its circumference. First allow time for each
group to collect the measurements of each of the three tins. Then collect the class results to
ensure that all pupils have accurate measurements. Then give pupils the table with the previously
collected results and get them to add the correct measurements for the tins. Ask pupils to
calculate how many times bigger each circumference is than the diameter. Introduce the concept
of Pi. Pupils to use mini whiteboards to give rough estimates and then more accurate estimates for
the circumference of different circles. Then pupils to work in groups to complete the missing
measurements in the table.
Plenary
Probing Question for mini white boards - What is the minimum information you need to be able to
find the area of a circle.
LO To calculate the perimeter (circumference) of a circle.
RAG
Key Words : Radius, Diameter, Circumference, Pi
08/04/2015
Level
3
4
5
6
7 /8
Shape
Space
Measure
I can
accurately
measure
using a tape
measure.
I can roughly
estimate the
(circumferenc
e) of a circle.
I can more
accurately
estimate the
perimeter
(circumference )
of a circle.
I can calculate the
radius, diameter or
circumference of
circles and semi circles
when given one other
measurement.
I can calculate
volumes and
surface area of
cylinders.
My target level is ________
I am starting the lesson on level _____________________
By the end of this lesson I want to be able to _____________________
Starter Activity
Mini white boards ready!!!!!!!!
Round this numbers to 1 decimal place.
2.3567
2.4
Starter Activity
Mini white boards ready!!!!!!!!
Round this numbers to 1 decimal
place.
12.3519
12.4
Starter Activity
Mini white boards ready!!!!!!!!
Round this numbers to 1 decimal place.
22.8915
22.9
Starter Activity
Mini white boards ready!!!!!!!!
Round this numbers to 1 decimal place.
25.6781
25.7
Starter Activity
Mini white boards ready!!!!!!!!
Round this numbers to 1 decimal place.
546.7899
546.8
Starter Activity
Mini white boards ready!!!!!!!!
Round this number to 1 decimal place.
0.12572
0.1
Starter Activity
Mini white boards ready!!!!!!!!
Round this numbers to 1 decimal place.
3.5689
3.6
Starter Activity
Mini white boards ready!!!!!!!!
Round this numbers to 1 decimal places.
26.9999
27.0
In your books sketch a circle and label the
parts using the key words.
People first realised that there is a connection between
the radius of a circle and its the circumference when
they realised that the longer the piece of string they
used to tether their goats, the bigger the circular patch
of grass they could eat.
Eratosthenes was born 194 years BC, long before calculators,
space ships and computers where invented and yet he was
able to calculate the circumference of the Earth amazingly
accurately.
In today’s lesson your task is to investigate the
relationship between the diameter of the
circle and the circumference.
In other words
How many times bigger is the Circumference
than the Diameter?
You have 3 Minutes!
• In your groups use the tape measures
provided to measure:a) the diameter
b) the circumference
of each tin and record the measurements in
the table provided.
Tin
Diameter
Circumference
Diameter
Circumference
Sweet Corn
Tuna
Beans
Tin
Sweet Corn
Tuna
Beans
To check the accuracy of your
measurements we are going to collect
the class results.
Baked Beans Diameter Circumference
To check the accuracy of your
measurements we are going to collect
the class results.
Tuna
Diameter Circumference
To check the accuracy of your
measurements we are going to collect
the class results.
Sweet Corn Diameter
Circumference
Add the class results to these results that I collected earlier. As a
group decide how to work out how many times bigger the
circumference of each circle is than the diameter.
As a group discuss what you notice about these results.
Object
Diameter
Circumference
Clock
20 cm
62.8 cm
Bin
28 cm
87.9 cm
Glue
3 cm
9.4cm
Sweet Corn
Tuna
Beans
How many times
bigger the
Circumference is
than the diameter.
The blue dot and the red dot are travelling at the same speed.
How many times do you think the red dot will travel across the
circle while the blue dot travels around the edge?
Once across
twice across
three times across
and a bit further!
So the Circumference of the circle is a little bit more
than 3x bigger than the diameter.

The
symbol is the Greek letter
pi. It represents how many times
bigger the circumference of any
circle is than its diameter.
The

symbol
represents 3.14159.........
To one decimal place the
Circumference of any circle is 3.14
times bigger than the diameter.
Mini White Boards Ready .......
Roughly how big is
the Circumference
of this circle ?
How can we be
more accurate?
Roughly how big is
the Circumference
of this circle ?
How can we be
more accurate?
Roughly how big is
the Circumference
of this circle ?
How can we be
more accurate?
Roughly how big is
the Circumference
of this circle ?
How can we be
more accurate?
If the Circumference is
36m roughly how big is
the diameter ?
How can we be
more accurate?
In your groups find the circumferences of the
circles and put the letters in the
corresponding answer box.
3
j:
e:
n:
m:
25.12
12.56
31.4
31.4
6.28
18.84
69.08
62.8
62.8
28.26
25.12
!
5
w:
o:
1
8
4
a:
11
i:
9
10
Success Criteria – Learning Outcomes
I measured accurately using a tape measure (Level 3).
I roughly estimated the circumference of circles by
multiplying the diameters by 3 (Level 4).
I estimated the circumference of circles by multiplying the
diameter by Pi (Level 5).
I calculated the radius, diameter or circumference of circles
and semi circles using one of the other measurements
(Level 6).
Plenary – Probing
Questions
What is the minimum
information you need to
be able to find the
Circumference of this
circle?