Delia (Man Kiu) English Primary School 1

Delia (Man Kiu) English Primary School

地利亞(閩僑)英文小學

Using scenarios with real examples to build the concept of Division of Fractions

HKU Sharing14/05/2021

Background

• 3 classes in the level

• Majority: India, Pakistani, Nepalese• Minority: Chinese, Filipino, Korean, Japanese, others

• About 1/3 each of low/medium/high achievement students. (Before pandemic)

Learning Objective:

• Know the calculation of division of fractions (Whole number divided by fraction)

• Know while the dividend is constant, the divisor becomes smaller, then the quotient will become larger.

Minecraft

• You have 6 biscuits now. You eat 3 biscuits a day. How many days can you survive?

• You have 6 biscuits now. You eat 2 biscuits a day. How many days can you survive?

• You have 6 biscuits now. You eat 1 biscuit a day. How many days can you survive?

• You have 6 biscuits now. You eat 𝟏𝟐 biscuit a day. How manydays can you survive?

6 ÷ 3 = 26 ÷ 2 = 36 ÷ 1 = 66 ÷ 𝟏

𝟐 = 12

You eat 𝟏𝟐 biscuit a day. You survive for 12 days.

Delia (Man Kiu) English Primary School 15

Delia (Man Kiu) English Primary School 16

You have one pizza only.

If you eat 𝟏𝟐

of the pizza a day. How many days can you survive?

If you eat 𝟏𝟒 of the pizza a day. How many days can you survive?

If you eat 𝟏𝟖 of the pizza a day. How many days can you survive?

If you eat 𝟏𝟑

of the pizza a day. How many days can you survive?

If you eat 𝟐𝟑

of the pizza a day. How many days can you survive?

Delia (Man Kiu) English Primary School 24

Delia (Man Kiu) English Primary School 25

Delia (Man Kiu) English Primary School 26

Delia (Man Kiu) English Primary School 27

Learning Objective:

• Understand the meaning of reciprocals and find reciprocals of numbers.

• Able to divide fractions by fractions.

Spring Baking Activity

• 8 ÷ 8 = 1• 8 ÷ 4 = 2• 8 ÷ 2 = 4• 8 ÷ 1 = 8

• 8 ÷ !"

= 16

• 8 ÷ !#

= (24 or 32?)

• 6 ÷ 6 = 1• 6 ÷ 3 = 2• 6 ÷ 2 = 3• 6 ÷ 1 = 6

• 6 ÷ !"

= 12

Case Study:

• Q1a. Mr. Cheng cuts the chocolate pie into 2 equal parts. He gives 1 part to Mr. Tam. How much of a chocolate pie does Mr. Tam take?

Case Study:

• Q1a. Mr. Cheng has a chocolate pie and he gives half of the pie to Mr. Tam. How much of a chocolate pie does he get?

Case Study:

• Q1b. Mr. Cheng cuts a chocolate pie into 4 equal parts. He gives 1 part to Ms. Antonia. 1 ÷ 4

= !"

• Q1b. Mr. Cheng has a chocolate pie and he gives a quarter of the pie to Ms. Antonia. How much of a chocolate pie does she get?

1 x !"

= !"

Comparison …

• 1 ÷ 2 = !#

• 1 ÷ 4 = !"

• 1 ÷ 8 = !$

• 1 x !#

= !#

• 1 x !"

= !"

• 1 x !$

= !$

Case Study:

• Q2a. Mr. Cheng has 4 chocolate pies and he put one third of a chocolate pie on a plate, how many plates does he need?

Case Study:

• Q2a. Mr. Cheng has 4 chocolate pies and he put one third of a chocolate pie on a plate, how many plates does he need?

4 ÷ !"

= 12

Case Study:

• Q2a. Mr. Cheng has 4 chocolate pies and he put one third of a chocolate pie on a plate, how many plates does he need?

Case Study:

• Q2b. Mr. Cheng has 4 chocolate pie and he put two third of a chocolate pie on a plate, how many plates does he need?

Case Study:

• Q2b. Mr. Cheng has 4 chocolate pie and he put two third of a chocolate pie on a plate, how many plates does he need?

4 ÷ #"

= 6 1st

1st

2nd

2nd

3rd

3rd

4th 4th

5th

5th 6th

6th

He needs 6 plates

Case Study:

• Q2b. Mr. Cheng has 6 chocolate pie and he put three fourth of a chocolate pie on a plate, how many plates does he need?

2nd

2nd

2nd

3rd

3rd

3rd 4th

4th 4th

5th 5th

5th 6th

6th

6th

7th

7th

7th 8th

8th 8th

1st 1st

1st

He needs 8 plates

Comparison …

• 1 ÷ 2 = !#

• 1 ÷ 4 = !"

• 1 ÷ 8 = !$

• 4 ÷ !%

= 12

• 4 ÷ #%

= 6

• 6 ÷ %"

= 8

• 1 x %& = %&• 1 x %' = %'• 1 x %( = %(

• 4 x )% = 12

• 4 x )& = 6

• 6 x ') = 8

Reciprocal

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