Subtraction and
Rounding
Number
Subtraction
Estimate differences within 99.
Subtract numbers, with and without renaming, within 99.
1.
2.
3.
4.
Use the symbols +, - , =.
Construct number sentences and number stories.
Estimate differences within 99 by subtracting the tens.
Check estimates using manipulatives.
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1. Applying and problem-solving: Select appropriate materials and processes for mathematical
tasks and applications. Select and apply appropriate strategies for completing a task or solving a
problem.
2. Communicating and expressing: Discuss and record the results of mathematical activities
using diagrams, pictures and symbols.
3. Implementing: Devise and use mathematical strategies and procedures for carrying out
mathematical tasks.
4. Integrating and connecting: Recognise the relationship between verbal, concrete, pictorial and
symbolic modes of representing numbers.
5. Reasoning: Make estimations and carry out operations to test them.
6. Understanding and recalling: Understand and recall terminology and facts.
Beads, counters, number lines, sweets, materials for measuring (e.g. jugs, rulers, clocks, weighing
scales), any materials that can be subtracted or used to illustrate subtraction techniques
Listen, estimate, take(n) away, complete, reduced, sale, added to, more, most/least,
altogether, difference, same as, doubles, nearest ten, number sentence, target, largest,
doubles, estimate, check, order, number line, picture story, problem, subtract
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General lesson suggestions
1. Jeopardy
The teacher and children stand in a line one behind the other. The teacher begins by giving an
answer, e.g. 20 and passes the ball over his/her head to the child standing behind, who then says
the question, e.g. ‘What is 10 + 10?’ This child then chooses another answer and passes the ball
under their legs to the next child who answers this question, etc.
2. Number bingo
The teacher distributes a bingo card to each child with number bonds on it. The teacher calls out a
number, e.g. ‘10’, and if a child has 24 – 14 they cover it with a counter.
3. Pairs
The children play this game using 10 cards (5 pairs) with number bonds shown as commutative
sums on each card. The children turn over 2 cards at a time. If the cards match, the child keeps the
cards. The winner of the game is the child with the most pairs at the end of the game.
4. Beat the clock
Give the children a number to work with. Time them for a minute to come up with as many
different facts about that number as possible.
5. Roll the ball
The teacher and children form a circle. The teacher calls out a number fact, e.g. 31 – 3 = 28 and
then rolls the ball to a child. That child then rolls the ball to another child who must say the sum in
a different way and roll the ball to someone else, and then another person who eventually says it
the last way.
Activity A
Call out the following numbers to the children and ask them to circle/cross out/shade/triangle
the nearest 10 to the numbers: 9, 59, 31, 1, 49, 98, 82, 69, 18,
42, 28, 94.
Lesson suggestions
Recall strategies for addition (nearest ten, number trios, counting on, doubles, friendly numbers,
etc.) and investigate how they can be applied to subtraction.
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Introduce rounding using playing cards. With the whole class set the criteria for a card game such
as near 0, near 5 and near 10. In pairs, allow Child A to pick a card from the deck, Child B must
decide whether the number/court card is closer to 0, 5 or 10.
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Ask the children to look at the number bonds in Section A. The children put a counter on the sum
that would be used to estimate various sums: 31 – 9 (i.e. 30 – 10), 61 – 49, 53 – 27, 41 – 28,
82 – 69, 19 – 9, 52 – 41, 42 – 18, 91 – 49.
Differentiation
Lower attainers:
Separate activity sheet
Higher attainers:
Separate activity sheet
A. Use the number line to help you subtract.
1
2
3
4
5
Subtract. Use rounding to help you work out the answer.
6
7
8
9
10
1.
6 8
–
2.
6
5 4
–
3 2
–
3 0
–
2 2
–
3 0
–
9 2
3.
8 4
–
6 4
–
4 3
–
4 0
–
1 5
4.
4 5
–
1 3
–
3 1
–
1 1
–
2 1
1. 10 – 9 = ___
5.
2. 10 – 7 = ___
3 5
–
3. 10 – 5 = ___
6.
2 5
5 6
7.
6 6
8.
4 5
4. 10 – 6 = ___
5. 10 – 8 = ___
9.
1. 20 – 9
8 9
–
B. Use what you know about 10 to help you subtract.
10.
4 2
3 2
11.
7 7
12.
4 2
= ___
2. 30 – 11 = ___
13.
3. 50 – 29 = ___
9 6
–
14.
6 8
5 0
15.
4 7
16.
5 9
4. 70 – 23 = ___
5. 90 – 43 = ___
17.
Name: _______________________________________
Date: ___________________
177
7 7
–
5 6
18.
9 3
Name: _______________________________________
Date: ___________________
Folens Photocopiables © Michelle Hande, Veronica Ward
8. 34 – 20 = ___
9. 28 – 10 = ___
10. 56 – 20 = ___
Folens Photocopiables © Michelle Hande, Veronica Ward
6. 63 – 40 = ___
7. 47 – 30 = ___
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Linkage
Number: Counting and numeration, comparing and ordering
Measures: Length, money
Integration
PE: Co-ordination – Throwing, catching and rolling
Parents can encourage children to use subtraction and mental maths in the everyday life
situations in the home, e.g. shopping, laundry and cooking.
Notes
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