Download northbrook primary school - Herne Junior School Kent

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts

History of logarithms wikipedia , lookup

Addition wikipedia , lookup

Arithmetic wikipedia , lookup

Transcript
PROGRESSION THROUGH CALCULATIONS FOR DIVISION
MENTAL CALCULATIONS
*** Mental calculation needs to be taught for the children to become efficient***
These are a selection of mental calculation strategies:
See ‘Teaching Children to Calculate Mentally’, pages 8 -11 for progression statements and
pages 51 -71 for strategies to teach.
Doubling and halving
Knowing that halving is dividing by 2
Deriving and recalling division facts
Tables should be taught everyday from Y2 onwards, either as part of the mental oral
starter or other times as appropriate within the day.
Year 2
Year 3
Year 4
Year 5 & 6
2 times table, 5 times table, 10 times table
2 times table, 3 times table, 4 times table, 5 times table
6 times table, 10 times table
Derive and recall division facts for all tables up to 10 x 10
Derive and recall quickly division facts for all tables up to 10 x 10
Using and applying division facts
Children should be able to utilise their tables knowledge to derive other facts.
e.g. If I know 3 x 7 = 21, what else do I know?
30 x 7 = 210, 300 x 7 = 2100, 3000 x 7 = 21 000, 0.3 x 7 = 2.1 etc
Dividing by 10 or 100
Knowing that the effect of dividing by 10 is a shift in the digits one place to the right.
Knowing that the effect of dividing by 100 is a shift in the digits two places to the right.
Use of factors
378 ÷ 21
378 ÷ 3 = 126
126 ÷ 7 = 18
378 ÷ 21 = 18
Use related facts
Given that 1.4 x 1.1 = 1.54
What is 1.54 ÷ 1.4, or 1.54 ÷ 1.1?
MANY MENTAL CALCULATION STRATEGIES WILL CONTINUE TO BE USED. THEY
ARE NOT REPLACED BY WRITTEN METHODS.
*Please see vocabulary book
THE FOLLOWING ARE STANDARDS THAT WE EXPECT THE MAJORITY OF CHILDREN
TO ACHIEVE.
Foundation Phase
Until children are ready for written calculation, they need to have a secure understanding
of:
 Number - recognise, count, order, write and use numbers up to 10 (progression up to
20).
 Vocabulary related to division as sharing*
 Counting in ones, twos, and tens.
 Recognising and understanding equal sized groups
During all of these play based activities teachers and staff will support children’s
developing knowledge by representing quantities (at first) and then calculations (not using
the division symbol, but as repeated subtraction), either by drawing pictures or symbols or
by writing numerals.
Children develop ways of recording calculations, using pictures.
Lower Phase
Children will understand equal groups and share items out in play and problem solving.
They will count in 2s and 10s and later in 5s.
Children will use vocabulary related to division*
*Please see vocabulary book
Children will develop their understanding of division and use jottings to support calculation

Sharing equally
6 sweets shared between 2 people, how many do they each get?

Grouping or repeated subtraction
There are 6 sweets, how many people can have 2 sweets each?
Repeated subtraction using a number line or bead bar

12 ÷ 3 = 4
0
1
2
3
4
3
5
6
7
3
8
9
10 11 12
3
3
The bead bar will help children with interpreting division calculations such as 10 ÷ 5 as ‘how
many 5s make 10?’ Therefore beginning to relate division to the inverse, multiplication.

Using symbols to stand for unknown numbers to complete equations using inverse
operations
÷2=4
*Please see vocabulary book
20 ÷  = 4
÷=4
Repeated subtraction using a number line or bead bar with remainders

13 ÷ 3 = 4 remainder 1 or r1
0
1
2
3
4
5
6
7
8
9
10 11 12 13
Middle Phase
Ensure that the emphasis in Y3 is on grouping rather than sharing.
Children to use the vocabulary related to division*
Children will continue to use:

Repeated subtraction using a number line
Children will use an empty number line to support their calculation.
24 ÷ 4 = 6
0
4
8
12
16
20
24
Children should also move onto calculations involving remainders, using an empty number
line.
13 ÷ 4 = 3 r 1
0 1

5
9
13
Using symbols to stand for unknown numbers to complete equations using inverse
operations
26 ÷ 2 = 
24 ÷  = 12
 ÷ 10 = 8
Children will develop their use of repeated subtraction to be able to subtract multiples of
the divisor. Initially, these should be multiples of 10s, 5s, 2s and 1s – numbers with which
the children are more familiar.
72 ÷ 5
0
2
-5
7
12
-5
17
-5
*Please see vocabulary book
22
-5
-5
27 32 37
-5
-5
-5
42 47 52
-5
-5
-5
57 62
-5
67
-5
-5
72
Moving onto:
02
r2
1
-5
7
1
-5
12
1
17
-5
1
22
-5
10
-50
(10x 5)
(1x 5)
(1x 5)
(1x 5)
(1x 5)
Then onto the vertical method (Chunking):
TU ÷ U
72 ÷ 3
3 ) 72
- 30
42
- 30
12
6
6
6
0
Answer :
10x3
10x3
2x3
2x3
24
Leading to subtraction of other multiples.
96 ÷ 6
16
6 ) 96
- 60
36
- 36
0
Answer :
10x6
6x6
16
Any remainders should be shown as integers, i.e. 14 remainder 2 or 14 r 2.
Children need to be able to decide what to do after division and round up or down
accordingly. They should make sensible decisions about rounding up or down after division.
For example 62 ÷ 8 is 7 remainder 6, but whether the answer should be rounded up to 8 or
rounded down to 7 depends on the context.
*Please see vocabulary book
e.g. I have 62p. Sweets are 8p each. How many can I buy?
Answer: 7 (the remaining 6p is not enough to buy another sweet)
Apples are packed into boxes of 8. There are 62 apples. How many boxes are needed?
Answer: 8 (the remaining 6 apples still need to be placed into a box)
Upper Phase
Children will use vocabulary related to division*
Children will continue to use written methods to solve division TU ÷ U.
Children can start to subtract larger multiples of the divisor, e.g. 30x
HTU ÷ U
196 ÷ 6
32 r 4
6 ) 196
- 180
30x 6
16
12
2x 6
4
Answer :
32 remainder 4 or
32 r 4
Any remainders should be shown as integers, i.e. 14 remainder 2 or 14 r 2.
Children need to be able to decide what to do after division and round up or down
accordingly. They should make sensible decisions about rounding up or down after division.
For example 240 ÷ 52 is 4 remainder 32, but whether the answer should be rounded up to
5 or rounded down to 4 depends on the context.
Children will continue to use written methods to solve division TU ÷ U and HTU ÷ U. Then
moving onto:
HTU ÷ TU
972 ÷ 36
27
36 ) 972
- 720
252
- 252
0
Answer :
*Please see vocabulary book
20x 36
7x 36
27
Any remainders should be shown as fractions, i.e. if the children were dividing 32 by 10,
the answer should be shown as 3 2/10 which could then be written as 3 1/5 in it’s lowest
terms.
Extend to decimals with up to two decimal places. Children should know that decimal
points line up under each other.
87.5 ÷ 7
7)
-
12.5
87.5
70.0
17.5
14.0
3.5
3.5
0
10x
2x
0.5x
Answer :
12.5
The children should also be taught that when dividing a number by a single digit they might
decide to use the short division method
875 ÷ 7=
125
7)875
3
1
This method can also be used to when finding a decimal fraction as an answer
362 ÷ 8 = 45.25
0 4 5. 2 5
8 ) 3 6 2. 0 0
3
*Please see vocabulary book
4
2
4