Strategies for Addition
Maths - Integers and Decimals
Mrs Booth
2
Exercise book or paper
Pencil
Image credit: Pixabay
In this lesson, you will need:
3
Starter quiz
Estimation
Mental Addition Strategies
Independent Worksheet
Exit quiz
Keywords
Place value - the value of a digit depending on its position within a number.
Strategies- a carefully developed plan or method for achieving a goal or the skill in developing and undertaking such a plan or method.
Solve- an answer to a problem.
Addition- when you put together two or more numbers together to find the total amount. The result of adding two or more numbers is called the sum.
4
Keywords
Commutative Law - The law of commutativity means that a group of numbers connected by the operations of addition or multiplication give the same result regardless of the order. For example, 7+5 is the same answer as 5+7
Number Bond - is a simple addition of two numbers that add up to give the sum.
5
6
Recapping Estimation
7
What is the nearest 10 to (when rounded up):
8
10
17
20
28
30
65
70
95
100
795
800
How can we use estimation in everyday life?
8
9
Image credit: Canva
10
$4.95
$3.25
$3.75
$2.50
$15
$5.00
$3.00
$4.00
$3.00
$8
+
$4
$12
+
$3
Image credit: Canva
11
$3.35
$1.25
$3.50
$5.50
$15
Image credit: Canva
Now it is your turn
12
$3.35
$1.25
$3.50
$5.50
$14
Image credit: Canva
$3
$1
$4
$6
Let’s see how you went!
How can we use the ‘round and adjust strategy’ to help us solve problems?
13
Round and adjust
14
27
30
+3
75
45
45
-3
72
+
Round and adjust is useful when a number is close to another ‘friendly’ number. Useful to avoid the need for regrouping.
Round and adjust
15
147
150
+3
421
271
271
-3
418
+
16
Round and adjust
B. 1355 + 1220 =
1234
1230
+6
1780
545
550
-10
1770
+4
+
1355
1360
+5
2580
1220
1220
-5
2575
+
Round and adjust
Have a go at solving this addition problem using the round and adjust strategy. You can round and adjust both addends.
17
398
400
+2
740
337
340
-5
735
+3
+
How can we use number bonds to help us solve problems?
18
Number Bonds
10
10
5
5
6
4
100
100
50
50
60
40
1000
1000
500
500
600
400
19
Number Bonds
8
9
4
4
6
3
80
90
40
40
6
3
60
30
20
Number Bonds
85
80
5
80 + 5
15
70
25
60
70 + 15
21
Now it is your turn to see if you can find some number bonds for 72.
72
80 + 5
70 + 15
60 + 25
85
22
Let’s see how you went!
72
70
2
70 + 2
12
60
22
50
60 + 12
50 + 22
23
24
Using Number Bonds in Addition
297 + 60
300
Let’s have a look at using these with addition problems.
?
?
3
57
300 + 57
= 357
25
125 + 45
?
?
Now it is your turn to see if you can mentally do this addition using number bonds.
26
125 + 45
130
?
?
5
40
130 + 40
= 170
27
125 + 45
130
130 + 40
= 170
125 + 45 = 170
28
How can we use the ‘bridge to the next ten’ strategy to help us solve problems?
29
30
Bridge to 10 strategy
40
47
34
+6
+7
13
34 + 13
31
Bridge to 10 strategy
130
174
123
+7
+4
51
123 + 51
170
+40
32
?
=
45
?
?
23
45 + 23
33
50
68
45
+5
+18
23
45 + 23
How can we use the ‘jump strategy’ to help us solve problems?
34
35
54
59
34
+20
+5
25
34 + 25
36
186
188
156
+30
+2
32
156 + 32
37
495
515
395
+100
+10
120
395 + 120
+10
505
Now it is your turn to see if you can mentally do these additions using the jump strategy.
38
46 + 32
215 + 82
529 + 259
39
76
78
46
+30
+2
32
46 + 32
40
295
297
215
+80
+2
82
215 + 82
41
729
788
529
+200
+50
259
529 + 259
+1
779
780
+8
42
Pause the video to complete your task
Resume once you’re finished
Independent Worksheet
Now it is your turn to independently practise using different mental strategies to solve addition algorithms. You will need to open the Worksheet named “Strategies for Addition”.
Worksheet Answers
43
279 + 81
280
?
?
1
80
280 + 80
= 360
44
Number bonds strategy -
392 + 78
400
?
?
8
70
400 + 70
= 470
45
Number bonds strategy -
46
90
120
83
+7
+30
37
83 + 37
Bridge to 10 strategy
47
852
879
752
+100
+20
125
752 + 125
+5
872
Jump strategy
48
Choose a strategy to answer the following: number bonds, jump or bridge to 10.
ADDITION SUM | ANSWER | STRATEGY USED |
86 + 42 | 128 |
|
517 + 633 | 1150 |
|
153 + 87 | 240 |
|
49
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