Download Subtraction - Horton Grange Primary School

Prior skills
Know vocabulary, less than, take
away.
Know the quantity of a number.
Method for Subtraction
Step 1
Taking away e.g 6-2
Becomes
Practise
Practical experience of taking
away.
Counting back verbally, on
labelled counting stick,
numberline etc.
Be able to count back on a
Step 2
number line.
Take away using a numbered number line.
Count back from a given number.
Understand that counting back is
8 -5 = 3
taking away.
Be able to practically take away
using objects.
Understand that when taking away 0 1 2 3 4 5 6 7 8 1
objects you end up with less.
Circle the starting number and count back 5. As this
is counting back, you should show this under the
line.
Counting back verbally.
Counting back from any number.
Counting back on number line.
Counting back on (labelled, partly
labelled, blank) counting stick.
Counting back on 100 square.
Continue this method of taking away only when
subtracting a small number eg, 11 take away 3 or
1004 take away 6 etc.
Knowledge of number bonds to 10. Step 3
Use number bonds to 10 to work
out bonds to other multiples of 10 Finding the difference (counting on) using a
e.g. 27+?=30
numbered, then partly numbered, number line.
Be able to understand the concept
of ‘difference’ through comparing
horizontal towers of multilink
cubes or other practical
equipment.
Experience of counting on from
the smallest number to the
largest.
Practical equipment to find the
difference e.g. towers of cubes,
beads on bead string, ITP
difference.
Discussions of the word
‘difference’.
Practise on numbered lines, then
partly numbered lines.
15 – 11 = 4
0
1 2 3 4 5 6 7 8 9 10 1112 13 14 15
Data handling experiences of
‘how many more/fewer?’
Be able to answer questions
Step 4
beginning with How many
more………..? eg. I need 20 straws
Find the difference using blank number lines.
for the milk. I already have 13.
Eg. 67-48=
How many more do I need?
Count on from a given number.
Number bonds to 10.
Be able to use number bonds to 10
and apply these to other multiples
+10
+2
+7
of 10 e.g. 7 + ? = 10 so, 27 + ? =30.
Compliments to 100.
0
48 50
60
67
Have a secure relevant method for
addition.
Keep 0 on the line until children are confident with line
and question why they need to draw the line back to 0.
NB Teachers model refining the jumps by combining
multiples of 10 , tens and units etc.
Recognise that the blank
Step 5
numberline need only cover the
Move onto line without 0 when children see that they
numbers and those in between the don’t need it.
numbers in the algorithm.
67 – 48 =
+10
+2
48
50
+7
60
67
NB Teachers model refining the jumps by combining
multiples of 10 , tens and units etc.
Experience of counting on from
the smallest number to the
largest.
Refine steps to fewest possible.
Apply to money, measures, data
handing etc.
Data handling experiences of
‘how many more/fewer?’
Apply to money, decimals,
measures, time, data handling.
etc.
Children need to be able to see
number lines in their head.
Children need to be able to
verbally explain their jumps along
the numberline and explain what
they land on.
Be confident with column
addition.
Be confident with place value.
Step 6
Use written method for finding difference.
391- 276=
+24
276 300
(276)
24 (300)
+1 91 (391)
115
+91
This is my
mental
picture.
391
This is what I write
down. The numbers in
brackets are the
numbers I land on.
Remember to carry above the answer box.
NB Continue to use a blank
number line for time and
decimals.
Progression
a
2 digit – 2 digit
digit
&
3 digit – 3
65 – 58
&
185 - 178
Jumps of units only.
b
2 digit – 2 digit
digit
&
3 digit – 3
55 – 38
&
165 - 133
Including jumps of 10.
c
3 digit – 2 digit
digit
&
3 digit – 3
134 – 84
&
423 – 376
Crossing a hundreds boundary.
d
3 digit – 3 digit
digit
&
3 digit – 2
921 – 345
&
523 - 42
Crossing more than one hundreds
boundary.
e
As above but extended to four digits.
7356 – 4802
&
3429 - 217
f
Extend to decimals & time.
465.15 – 274.87 &
NB.
12:34 – 7Hrs 50m
Crossing more than one thousands
boundary.
(Relate time to 60 min boundaries)
When subtracting a number which is less than 10, from any other number (large or small) use the ‘count back’ method as opposed to the ‘find
the difference’ method.