Unit 3 Let's do math! lesson 17课件(共16张PPT)

(共16张PPT)
LET'S DO MATH!
lesson 17
20~90的十位数的整数均以后缀-ty结尾
20 twenty 30 thirty
40 forty 50 fifty
60 sixty 70 seventy
80 eighty 90 ninety
Again
20
30
40
50
60
twenty
thirty
forty
fifty
sixty
70
80
90
100
seventy
eighty
ninety
one hundred
Let’s do it
There are forty bananas.
My brother took away ten.
How many bananas are left
40-10=30
Forty minus ten is thirty.
Thirty bananas are left.
There are fifty apples.
My sister took away twenty.
How many apples are left
50-20=30
Fifty minus twenty is thirty.
Thirty apples are left.
There are fifty eggs.
My mother took away thirty.
How many eggs are left
50-30=20
Fifty minus thirty is twenty.
Twenty eggs are left.
There are sixty pears.
My father took away ten.
How many pears are left
60-10=50
Sixty minus ten is fifty.
Fifty pears are left.
Practice
1. 90-20=
2. 80-20=
Ninety minus twenty is________.
Eighty minus twenty is________.
One hundred minus twenty is________.
3. 100-20=
seventy
sixty
eighty
Fifty minus thirty is________.
Sixty minus thirty is________.
Ninety minus forty is________.
4. 50-30=
5. 60-30=
6. 90-40=
twenty
thirty
fifty
Homework:
回家把今天学到的数字
数给爸爸妈妈听。
Thank You!