Lesson Plan – Lesson 4 Circumference

Mental and Oral StarterPupils to use the mini white boards to round numbers to one decimal place.

Main ActivityPupils 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.

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

RAGKey Words : Radius, Diameter, Circumference, Pi

LO To calculate the perimeter (circumference) of a circle.

21/04/23

Level 3 4 5 6 7 /8ShapeSpaceMeasure

I can accurately measure using a tape measure.

I can roughly estimate the (circumference) 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 ________

Today we are learning

I am starting the lesson on level _____________________

By the end of this lesson I want to be able to _____________________

Starter ActivityMini 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 ActivityMini 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 wordsHow 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 diameterb) the circumference of each tin and record the measurements in the table provided.

Tin Diameter Circumference

Sweet Corn

Tuna

Beans

Tin Diameter Circumference

Sweet Corn

Tuna

Beans

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

To check the accuracy of your measurements we are going to collect the class results.

Object Diameter Circumference How many times bigger the Circumference is than the diameter.

Clock 20 cm 62.8 cm

Bin 28 cm 87.9 cm

Glue 3 cm 9.4cm

Sweet Corn

Tuna

Beans

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.

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 acrosstwice across

So the Circumference of the circle is a little bit more than 3x bigger than the diameter.

three times acrossand a bit further!

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 ?

6cm

How can we be more accurate?

Roughly how big is the Circumference of this circle ?

5cm

How can we be more accurate?

Roughly how big is the Circumference of this circle ?

1000cm

How can we be more accurate?

Roughly how big is the Circumference of this circle ? 20cm

How can we be more accurate?

If the Circumference is 36m roughly how big is the diameter ?

?

How can we be more accurate?

j:

e:

w:

n:

o:

a:

m:

i:

25.12 12.56 31.4 31.4

6.28 18.84 69.08 62.8

62.8 28.26 25.12 !

3

1

5

8

4

11

10

9

In your groups find the circumferences of the circles and put the letters in the corresponding answer box.

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?