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Subtraction Workshop

Subtraction Workshop. Overview of workshop . Language of subtraction Progression of subtraction across Year 1 and 2 Questions Work alongside our children. Finding the difference. Minus. What words have you heard your child use when talking about subtraction ?. Subtract. Less than .

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Subtraction Workshop

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  1. Subtraction Workshop

  2. Overview of workshop. • Language of subtraction • Progression of subtraction across Year 1 and 2 • Questions • Work alongside our children.

  3. Finding the difference Minus What words have you heard your child use when talking about subtraction? Subtract Less than Take Away Repeated Subtraction

  4. Language, Language, Language! Bonds to 10 Single Digit Number Digit Three Digit Number Two Digit Number Bridging through 10 Fact Families Tens Partitioning Multiples of 10 Place Value Units Switchers

  5. Progression within subtraction. • Subtracting single digits. • Use practical equipment that can be moved physically. • Use pictures which the children point to as they count. +

  6. 7-2=5 • Use of a number track to jump back along • Use of a number line to jump back along. 7-2=5 • Use of a number square to count back along. 7-2=5

  7. Taking a single digit from a two digit number. • Number lines or a number track to count back along. • Knowledge of place value 27 - 4 207 4 20+ 3 23

  8. Dienes which model place value clearly. • Use of a blank number line. -4 27-4=23 23 27

  9. Taking away a single digit from a two digit number bridging through ten. 23– 9 Labelled number line to jump back Blank number line to jump back

  10. Use of number bonds to 10 to bridge through the nearest multiple of 10. 23- 9 20 33 6 23 - 3 = 20 20 - 6 = 14 -6 -3 14 20 23

  11. Taking away a multiple of ten from a two digit number. • 49 - 10 • Move up one to take away tens. • 65 – 30 • Move up three times to take away three lots of ten.

  12. Taking away a two digit number from a two digit number. • Number square • 49 - 14 • Move up one to take away tens. • Count back to take away units.

  13. Blank number line. -4 -10 39 49 35

  14. + Taking away a single digit from a three digit number. 364- 5 = 359 359 364

  15. + Taking away a two digit number from a three digit number. 364 + 25 Partition the hundreds Take away the tens from the first number 64 -20 = 44 Take away the units from this answer 44 -5 = 39 Add this answer to the hundreds

  16. + Taking away a three digit number from a three digit number. 385 -217 Take away the hundreds 300-200 =100 Take away the tens from the first number 85-10 = 75 Take away the units from the answer 75-7 = 68 Add hundreds to tens and units 100 + 68 = 168

  17. Taking away a three digit number from a three digit number crossing the hundreds or tens boundaries. 453 – 284 Only partition the second number. Take away the hundreds 453 – 200 = 253 Take away the tens 253 – 80 = 173 Take away the units 173 – 4 = 169

  18. Start to think of subtraction as finding the difference. 84 – 73 = ? What is the next multiple of ten after 73? 80 ? What is the gap to 80? ? What is the gap from 80 to 84? ? What is 7 + 4? 11 So 84-73 = 11

  19. 682 – 35 • ? What is the nearest 100 after 35? 100 • ? What is the gap to 100? • ? What is the gap from 100 to 682? • ? What is 582 + 65? • Partition the number • Add the tens : 80 + 60 = 140 • Add the units: 2+ 5 = 7 • Add these answers together 140 + 7 = 147 • Now add on the remaining hundreds 147+ 500 = 647 • So 682-35= 647

  20. Questions?

  21. What’s the Time? • Start at the end of the number line. • Label the number line at a level appropriate for your child, it could be hours, minutes, 30 second intervals etc. • With your child create some time cards eg watch TV – 30 minutes, Play on the computer – 1 hour, read a book – 2hours etc. • Take it in turns to choose a card, then work out the answer by jumping back along the number line. • The first person to get to the start of the number line is the winner.

  22. Be Careful! • Start at the top of the number line. • Label the number line at a level appropriate for your child, it could be intervals of 100ml, 10 ml etc • With your child create some capacity cards eg water the plants– 100ml, have a drink – 200 ml, fall over and tip the water – 500ml etc • Take it in turns to choose a card, then work out the answer by jumping back along the number line. • The first person to get to the start of the number line is the winner.

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