TOPIC
5
305.2 Subtract without and with renaming, within 999.
306.2 Know and recall subtraction facts.
307
Solve word problems involving addition and subtraction.
1. Subtraction as deducting, as complementing and as difference.
2. Mental subtraction, 0–20.
1. Applying and problem-solving: Select appropriate materials and processes for mathematical
tasks and applications.
2. Communicating and expressing: Discuss and explain the processes used or results of
mathematical activities/projects/ problems.
3. Integrating and connecting: Understand the connections between mathematical procedures
and concepts. Represent mathematical ideas and processes in different modes: verbal,
pictorial, diagrammatic, symbolic.
4. Reasoning: Explore and investigate mathematical patterns and relationships.
5. Implementing: Execute standard procedures efficiently with a variety of tools.
6. Understanding and recalling: Understand and recall terminology, facts and definitions.
Multi-link cubes, counters, dice
Subtract, less, difference between, rename
1. As with adding, when subtracting horizontally ensure the children understand
the importance of putting the numbers in the correct columns. This is not
something they will all automatically know how to do.
2. Ensure the children understand why we reduce the 10 by 1 and add 10 to the units when
decomposing a 2-digit number. A good way to explain this is with 100, 10 and 1 blocks. Show
that when they take one 10, it is actually the same as taking 10 units and it changes when it
moves into the unit column. This can really help children understand the process rather than
just doing what the teacher tells them to do.
Loop game (see Folens Planet Maths Resources):
Subtraction.
Fans:
Simple subtraction: 14 – 6 = , 22 – 10 = , 40 – 6 = When the children are confident move into
the hundreds,100 – 10 =, 100 – 20 =, 100 – 30 =, etc.
Target board 3:
Take 25 away from each number. This can be made harder (take 50 away from each number).
Hide and seek:
Write numbers on pieces of card and hide them around the room or playground. Give each child
a card with a number on it. They must then find 2 numbers whose difference makes their number,
e.g. if their number is 7 then they could find 10 and 3. Make sure there are plenty of cards so all
children can find a match, otherwise you could make it a knockout and any child who does not
find 2 correct cards is out.
Loop cards:
Children create a set of loop cards in pairs, e.g. card 1: ‘I am 10. Who is 15 minus 7?’ card 2:
‘I am 8. Who is the difference between 15 and 20?’, etc. Encourage children to use different
vocabulary throughout. See blank template.
Beat the teach:
Children stay seated, the teacher stands behind a child while another calls out a subtraction
problem. If the teacher answers first, then he or she moves on to the next student. If the student
answers first, their name is added to a Wall of Fame for those who Beat the Teach.
Human subtraction:
This is a great and fun way to help children understand subtraction with renaming. Write a
subtraction sum on the board and choose children to represent each digit from the top line of the
sum. Give each child a card with ‘H’, ‘T ‘or ‘U’ on it, e.g. for 254, there will be 2 children holding
a ‘H’, 5 holding a ‘T’ and 4 holding a ‘U’. Then begin subtracting: 4 – 6 you cannot do, so you will
need a 10 to move over to the unit side, etc.
Target board warm up
1. There are 12 birds sitting in a tree, 6 fly
away. How many are left?
2. Emma had 80c. She spent 40c on an apple
for her lunch. How much had she left?
3. Fill in the missing words:
20 ______ ______ 10 = 10.
4.
5.
6.
7.
8.
9.
Half of 16.
My answer is 17.
15 take away 3.
21 minus 6 = ______.
My answer is 16.
What is the difference between 7 and 10?
Lower attainers:
Separate activity sheet
Higher attainers:
Separate activity sheet
Topic
Topic
5
5
1. (a)
64
(b) 41
– 58
– 37
(c)
70
(d) 77
– 46
– 29
(e)
48
1. What’s the missing number?
– 29
(f) There are 78 pages in Nellie’s book. If she has read 49, how many more pages does she need
to read? ____________________
(g) There are 74 chairs in the school hall. If only 58 parents arrive for a meeting how many free
seats are there? ____________________
(h) It is 70 metres from one end of the school yard to the other. If Asher has run 56 metres how
– 50
– 87
– 12
– 36
– 23
– 35
– 18
– 26
– 32
– 43
0
0
0
0
(d) 800 + ______ = 999
(e) 500 + ______ = 892
(f) 793 + ______ = 895
(g) 256 – ______ = 167
(h) 789 – ______ = 367
(i) 681 – ______ = 278
(j) 689 – ______ = 378
(k) 999 – ______ = 444
(l) 300 – ______ = 167
centre number. The first one has been done for you.
(a)
2. Complete the following sums. Use the rough space below work out the answers.
(a) 45
(b) 86
(c) 105
(d) 165
– 24
(b) 267 + ______ = 781
(c) 478 + ______ = 789
2. Subtraction triangles. Find the difference between each corner number to give you the
much farther does he need to go to reach the other end? ____________________
– 15
(a) 346 + ______ = 589
(b)
12
4
(c)
47
8
23
5
68
95
3
3
(d)
Rough work!
(e)
68
(f)
200
167
14
46
(c) 751
(d) 681
(e) 627
– 378
– 285
– 392
– 539
306
(g) 500
(h) 249
– 258
– 256
– 207
(f)
(i)
400
– 163
(j)
267
145
467
278
3. Solve these problems
501
– 367
(k) There are 700 pupils in the local primary school. If 402 of them are boys how many girls are
(a) There are 780 people at a concert. 578 of these are adults. How many children are there?
_____________
in the school? ____________________
(l) For a charity event 900 balloons were let off in Dublin. 278 fewer than that were let off in
Cork, how many balloons did they let off in Cork? ____________________
111
(b) In Emily’s school library there are 976 books, 356 are fiction, 279 are non-fiction and 68 are
poetry books. How many teacher books are there? _____________
(c) At a school summer camp there were 456 boys. How many children were at the summer
camp if there were 67 more girls than boys? _____________
(d) A train pulled up to station with 875 people on board. 345 people got off and 478 got on.
How many more people are now on the train? _____________
© Folens Photocopiables
(b) 540
– 275
© Folens Photocopiables
3. (a) 543
46
7
112
Measures: Subtracting lengths, weights, capacities, time and money
SESE History: Calculating how long ago events happened and how long events lasted
SESE Geography: Calculating differences in mountain height, river lengths and populations
Encourage children to work out what change is owed when shopping and how much pocket
money they will have left if they buy something. In the kitchen, ask questions like, ‘How much
flour will be left if I use 200g?’
Notes
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