Game 1N5: Operations - Subtraction
Strand: Number
Strand Unit: Operations - Subtraction
Curriculum Objectives Covered:
Develop an understanding of subtraction as deducting, as complementing and as
difference 0-20
Develop and/or recall mental strategies for subtraction 0-20
Construct number sentences and number stories; solve problems involving subtraction 020
Estimate differences within 99
Subtract numbers without renaming within 99
Use the symbols +, - and =
Solve one-step problems involving addition or subtraction
Part 1: “Find a Number Sentence”
Aim: To find 4 other children in the play area who’s number/symbol cards will join with yours
to make any correct number sentence e.g. 15 – 4 = 11, within a time limit.
Activity Area: Hall, yard or open area.
Duration: 10 minutes
Integration:
Physical Education: Understanding and appreciation of games
Resources:
1 set of number cards 0-20 (use one set of 0-20 number cards from Game 1N4)
6 ‘=’ cards, 6 ‘-’ cards and 3 ‘+’ cards (photocopiable cards attached)
Tub of at least 200 plastic counters
1 whistle
Set Up:
1. Photocopy and cut out the attached =, - and + symbol cards.
2. Use one set of the 0-20 number cards from Game 1N4, and photocopy one of the 0-20
numbers again, to include that number twice. (This is to enable the ‘0’ card to be used in a
number sentence).
3. Create a ‘base’ area somewhere in the hall/play area and put the tub of counters in that area.
4. Shuffle the 22 number cards, the 6 ‘=’ cards, and the 6 ‘-’ cards together, and randomly give
each child one card.
5. The children spread out around the hall, taking positions anywhere they choose. Each child
holds his/her card in front of him/her, facing outwards, so that everybody can see everybody
Copyright Ann Moran
else’s number/symbol.
Start Playing:
1. The children have 3 minutes to complete each task.
2. When the teacher blows the starting whistle for the first time, each child must move quickly
around the hall to try to find 4 other children with number/symbol cards that would work
with his/hers to make a correct subtraction number sentence. E.g. a child with a card
showing the number 12 could find children with cards showing ‘-’, ‘7’, ‘=’ and ‘5’ to make
the correct number sentence 12 – 7 = 5.
3. It should be explained to the children that more than one group might be looking for the
same cards, so it is important to find your whole number sentence quickly.
4. The children can use the plastic counters in the base area to work on their number sentences
if necessary.
5. When 5 children are satisfied that they have a correct subtraction number sentence, they
must sit on the floor to show that they are finished. They should lay out their 5 cards on the
floor beside them, to clearly show their subtraction number sentence.
6. After the 3 minutes, the teacher blows the whistle again and everybody must freeze.
7. Any children sitting on the floor when the whistle is blown, with full correct number
sentences, receive 1 house point/reward each.
8. The teacher then collects the cards from the children for the next round.
9. The teacher removes 3 of the ‘-’ cards from the pile, and adds 3 ‘+’ cards.
10. The cards are again shuffled and dealt out, one to each child, and the children once again
spread out around the hall with their cards on view.
11. As before, the children have 3 minutes to complete the task.
12. This time, however, each child must try to find 4 other children to make a correct number
sentence using either a ‘+’ or a ‘-’ symbol. For example, 6 + 8 = 14, or 5 – 2 = 3.
13. The teacher blows the starting whistle and, as before, the children have 3 minutes to find 4
other children with suitable cards to join with to make a correct number sentence.
14. When 5 children are satisfied that they have a correct number sentence, they must sit on the
floor to show that they are finished. They should lay out their 5 cards on the floor beside
them, to clearly show their correct addition or subtraction number sentence.
15. After the 3 minutes, the teacher blows the whistle again and everybody must freeze.
16. Any children sitting on the floor when the whistle is blown, with full correct number
sentences, receive 1 house point/reward each.
Part 2: “How long can you stay in the game?”
Aim: To stay in the game for as long as possible by subtracting correctly.
Activity Area: Classroom
Duration: 20 minutes
Resources:
1 set of number cards 0-99 (use cards 0-99 from Game 1N3)
Copyright Ann Moran
1 ‘feely bag’
Paper and pencil for each child
Set Up:
1. The children sit at their desks, each with paper and a pencil.
2. The teacher stands at the whiteboard, with the cards 0-99 inside the feely bag.
Start Playing:
1. The teacher pulls out 2 cards at random from the feely bag and writes the numbers on the
whiteboard for subtraction
e.g.
86
- 42
(The children are practicing subtracting without renaming so the teacher must ensure that he/she
only uses suitable numbers, e.g. 67 – 49 would not be a suitable question.)
2. Before the children begin to work out each answer with their pencils and papers, the teacher
should encourage the children to put up their hands to suggest some estimates. They can
estimate an answer by subtracting the tens.
3. Each child then writes the question on his/her page and works it out.
4. When everybody has worked out the answer, the teacher works out the answer on the
whiteboard.
5. Any child who worked out the answer correctly stays in the game. Anybody who worked out
an answer incorrectly is knocked out of the game. (The children can verify the answers of
the children next to them.)
6. The teacher then pulls out another 2 suitable cards from the bag and writes up the new
question on the whiteboard.
7. Also, occasionally, instead of writing a question on the whiteboard, the teacher should make
up a number story involving subtraction 0-20 e.g. “If Thomas had 8 sweets but Nicola ate 3
of them, how many sweets would Thomas have left?” As before, the children write their
answers on their papers.
8. The play continues until there are only 15 players remaining in the game. Each of these
players receives 1 house-point/reward.
Copyright Ann Moran
Copyright Ann Moran
Copyright Ann Moran
Copyright Ann Moran