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##### Presentation Transcript

1. 243 - 167 35 – 14 11 take away 3 8 less than 40 Subtraction 632 minus 157 How do we do it? 1 2 3 4 5 6 7 8 9

2. Vocabulary introduced in the Reception class take/take away leave count on/back less difference between How many fewer is…..than….? How many have gone? How many are left over? How many more to make? 1 2 3 4 5 6 7 8 9

3. Further vocabulary Year 1 - subtract minus How much less is….? Year 2 - subtraction one hundred less Year 4 - decrease 1 2 3 4 5 6 7 8 9

4. Subtraction Progression in subtraction • Pictures and words 18 – 3 = 15 • Symbols • Informal jottings • Expanded methods – see next slides • Compact methods – more traditional methods • Calculator – used appropriately for large numbers 1 2 3 4 5 6 7 8 9

5. Subtraction The empty number line There are 34 children in the room, 27 go into the hall. How many are left? 34 - 27 = 7 +4 +3 27 30 34 7 children are left 1 2 3 4 5 6 7 8 9

6. Subtraction The empty number line – another way of using it The baker makes 54 loaves and sells 28. How many has he left? 54 - 28 = 26 - 20 - 8 26 34 54 26 loaves are left 1 2 3 4 5 6 7 8 9

7. Subtraction The empty number line – using near tens The baker makes 54 loaves and sells 28. How many has he left? 54 - 28 = 26 - 30 +2 24 54 26 26 loaves are left 1 2 3 4 5 6 7 8 9

8. Subtraction The empty number line – useful for money problems Mum went shopping and spent £13.42. She gave the Shopkeeper £20. How much change did she get? £20 - £13.42 = £6.58 + 50p +£6 +8p £13.42 £20 13.50 £14 £6.58 change 1 2 3 4 5 6 7 8 9

9. Subtraction The empty number line – makes time problems simpler The train leaves at 12.18 and arrives at 15.46. How long is the journey? The journey takes 3h 28m + 3h +16m +12m 12.18 15.46 12.30 15.30 1 2 3 4 5 6 7 8 9

10. 8 7 3 5 - - 7 5 80 30 50 2 5 2 Subtraction – the start of vertical methods 87 - 35 = For more examples of “arrow cards” see Addition presentation 1 2 3 4 5 6 7 8 9

11. 5 1 563 -248 315 Subtraction – steps to compact method 563 - 248 500 and 60 and 3 Decompose 60 into 50 and 10 -200 and 40 and 8 500 and 50 and 13 -200 and 40 and 8 300 and 10 and 5 1 2 3 4 5 6 7 8 9

12. 3 1 643 -358 285 5 1 500 and 130 and 13 -300 and 50 and 8 Subtraction – more complicated example 643 - 358 600 and 40 and 3 Decompose 40 into 30 and 10 -300 and 50 and 8 600 and 30 and 13 Decompose 600 into 500 and 100 -300 and 50 and 8 200 and 80 and 5 1 2 3 4 5 6 7 8 9

13. How can you help? Develop mathematics in real situations at home, e.g. cooking, shopping, setting the video. Play simple games, e.g. Ludo, Dominoes, Cribbage. Learn that mathematics is much more than calculations in a book or tests. Always try to boost your child’s confidence. If you aren’t sure about how your child is doing their calculations ask the teacher’s advice. Judge their ability by what they can do in their heads. Be positive about mathematics – It’s fun. 1 2 3 4 5 6 7 8 9