21st century modern mathematics 1c · 21st century modern mathematics 1c 12 11 there are 32 and 19...
TRANSCRIPT
1C 12 121st Century Modern Mathematics
Dimension: Number
Learning unit: 1N5 Addition and subtraction (I)
12 Addition (2)
21st Century Modern Mathematics
1C
1C 12 221st Century Modern Mathematics
1 How many toys are there?
I have 14
Funny Eggs.
I have 6
Funny Eggs.
1
Funny Eggs
1C 12 321st Century Modern Mathematics
1 How many toys are there?
T U T U
→
1
Total: 14 + 6 = 20
1C 12 421st Century Modern Mathematics
1 4
6+
T U
0
1 How many toys are there?
1
4+ 6
10
You can mark the number here.
1 4
6 +
T U
→
1C 12 521st Century Modern Mathematics
2 0
1 4
6+
1 4
6 +
1 How many toys are there?
1
4+ 6
10
1 + 1 = 2
→
When the units place adds up to 10,
carry 1 to the tens place.
T U T U
→
1C 12 621st Century Modern Mathematics
1 How many toys are there?
What will happen if I forget
to carry the number to the
tens place?
1C 12 721st Century Modern Mathematics
UT
15 soldiers
Total: 15 + 16 = 31
16 soldiers
1 How many toys are there?
How many toy soldiers are there?2
→
UT
1C 12 821st Century Modern Mathematics
1 How many toys are there?
2
1 5
1 6+
T U
1
1 5
1 6 +
T U5
+ 6
113 1
1 5
1 6 +
T U
Don’t forget
the carrying.
→ →
How many toy soldiers are there?
1C 12 921st Century Modern Mathematics
3 Look at the abacuses. Write the answers.
a 18 + 3 =
1 8
+ 3
UT
21
2 1UT
b 26 + 16 =
26
+ 16UT
42
42
1 How many toys are there?
1C 12 1021st Century Modern Mathematics
1 25
+ 5
30
2 8
+ 19
27
3 13
+ 37
50
4 46
+ 27
73
1 How many toys are there?
1C 12 1121st Century Modern Mathematics
There are 32 and 19 .
How many toy cars are there
altogether?
= 51
2 Counting toys
1
There are 51 toy cars altogether.
32 is close to30.
19 is close to 20.32 + 19 32
+ 19
51
The answer is close to:
30 + 20 = 50
1C 12 1221st Century Modern Mathematics
There were 24 at first.
48 are added.
How many teddy bears are
there altogether?
2
There are _____ teddy bears altogether.
=
+
+72
72
48
48
24 24
72
2 Counting toys
1C 12 1321st Century Modern Mathematics
There are _____ pianos.
=
There are 19 .
There are 11 more than .
How many pianos are there?
3
30
19 + 11 19
+ 11
30
Write the
column
form.
30
2 Counting toys
1C 12 1421st Century Modern Mathematics
Let’s do the activity, ‘Game of addition’, on
page 18 of Classroom Learning 1C.
2 Counting toys
1C 12 1521st Century Modern Mathematics
Look at the abacuses. Write the answers.
1
19
+ 5
19 + 5 = 24
24UT
27
+ 26
27 + 26 =2
UT
53
53
1C 12 1621st Century Modern Mathematics
Fill in the blanks.
3 8
+ 17
25
4 23
+ 8
31
5 64
+ 16
80
6 35
+ 28
63
1C 12 1721st Century Modern Mathematics
7 5249 + 3 = 8 7 + 54 =
9 15 + 76 = 25 + 35 =10
61
91 60
Fill in the blanks.
1C 12 1821st Century Modern Mathematics
There were 69 fish in the
tank. 18 fish are added.
How many fish are there
altogether?
11
=
+
+87
87
18
18
69 69
There are _____ fish
altogether.
87
Fill in the blanks.
1C 12 1921st Century Modern Mathematics
Interesting sums
Do you remember the
compositions of 10?
Let’s write them out.
Compositions of 10
1 + 9
4 + 6
7 + 3
5 + 5
8 + 2
6 + 4
9 + 1
2 + 8 3 + 7
1C 12 2021st Century Modern Mathematics
1 Do the sums using the compositions of 10:
a 8 + 3 = ?
10 + 1 = 11
2 1
Write 3 as 2 + 1, We can
add 2 to 8 to form 10.
Interesting sums
1C 12 2121st Century Modern Mathematics
1 Do the sums using the compositions of 10:
b 14 + 9 = ?
13 + 10 = 23
13 1
Write 14 as 13 + 1, We
can add 1 to 9 to form 10.
Interesting sums
1C 12 2221st Century Modern Mathematics
20 + =
b 16 + 5 = ?
+ 10 =
2 Let’s try.
a 16 + 5 = ?
21
5
11 21
4 1
1
11
Interesting sums
1C 12 2321st Century Modern Mathematics
3 Let’s do the sums using the above method.
a 13 + 9 = 22 b 24 + 7 = 31
Interesting sums