Transcript Presentation for Maths Evening (PowerPoint)

Help your child with
calculation strategies.
This is the way we do it!
“They didn’t do it like that
in my day!”
Do your children ask for help with their
numeracy homework?
Do they start talking in a foreign
language, using words you have never
heard of?
If so, you may feel you need some
translation. This session today is
designed to explain some of the
methods used to teach
calculation.
Which is more important? Mental
calculation? Written calculation?
This will depend on the size
of the numbers involved and the
individual child. When faced with a
calculation, no matter how large or
difficult the numbers may appear to
be, all children should ask
themselves the following:
Can I do this
in my head?
I can’t do all of it in my head, what
do I need to write down in order to
help me calculate the answer?
Do I know the
approximate size of the
answer?
the?
Will the written
method
I know be helpful?
Some of the methods we use
in school are:
 Column addition
 Number line subtraction
 Grid method multiplication
 Chunking for division
ADDITION
Number line
42 + 36 = 78
+ 30
42
+6
72
Add tens, then units
= 78
Partitioning (upside down mountains)
67 + 32 = 99
60+30 7+2
(90) + (9) = 99
Column addition
32
126
+ 45
+ 57
70 (30 + 40) 100 (100 + 0)
7 ( 2 + 5)
70 ( 20 + 50)
77
13 ( 6 + 7)
183
Brackets need not be used
once your child is
confident in this method.
Column addition
(carrying under the line)
438
+ 284
722
11
£ 1.67
+£ 2.45
£ 4.12
1 1
Extend to decimals making sure
the decimal points line up
under each other
Subtraction
Number line : Counting on
48 - 36 = 12
+4
36
+8
40
4 + 8 = 12
48
Subtraction
Partitioning (upside down mountains)
67 - 32 = 35
60-30 7-2
(30) + (5) = 35
The “minus method”
436
- 255
- 200 (400 – 200)
- 20 (30 – 50)
+ 1 (6 – 5)
181 (200 – 20 + 1)
Leading to
Decomposition
4 1
52
-2 7
25
The number line is still used to help with problem
solving when dealing with time.
Albert is going to visit his aunt. His journey takes
an hour and 45 minutes, he arrives at 4:15 pm,
what time did he start his journey?
-1hour
4:15
-15minutes
3:15
3pm
-30minutes
2:30pm
Multiplication
In Year 3 children are used
to using repeated addition:
5 x 3 = 15
+3 + 3 + 3 + 3 + 3
0
3
6
9
12
15
The grid method : 27 x 54 = 1458
Partition first into tens and units
x
20
50
1000
350
4
80
28
1080
7
+ 378 = 1458
Division
Repeated addition is used on a number line
15 ÷ 5 = 3
+5
0
+5
5
+5
10
= 15
15
Work on remainders is done
with the number line.
17 ÷ 5 = 3 r 2
+5
+5
0
5
+5
10
+2
15
Chunking
“Chunks” of the divisor are recorded
and used in repeated addition
72 ÷ 5 = 14 rem 2
0
+ 50 (10 x 5)
+ 20 (4 x 5)
70
+ 2 rem.
72
bank
10
4
14
Compact division or short
division is used when children
have developed Level 5 skills and
a secure understanding of place
value.
93 9
2 5
6
56 34
Thank you for attending,
we hope you’ve found it
useful.
Now please visit the
experts to see how it’s
done in practice!