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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
- THE END -
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