Presentation on theme: "Welcome to our Mathematics Evening"— Presentation transcript:
1Welcome to our Mathematics Evening Please take a seat
2First of all – 10 questions whiteboards ready! Don’t worry it isn’t too hard
3What is 134 less than 207?What is 207 minus 134?What is 207 subtract 134?What is the difference between 207 and 134?Can you decrease 207 by 134?
4From 134 how many more to make 207? What is 207 take away 134?What is the remainder when 134 blocks are removed from a pile containing 207?I had 207 books and lost 134 of them, how many does this leave?I have £207 and spend £134, how much do I have left?
5Subtraction Vocabulary You have just seen 10 different ways of asking the questionThere are other pieces of subtraction vocabulary as wellThe answer was 73You don’t always see the word subtraction when you have to subtract.
6Take an in depth look at subtraction. By… This evening we aim to…Take an in depth look at subtraction. By…Showing you how the children need to develop their subtraction skills through the year groups and levels.Looking at the non-mental methods we teach and the order in which we teach them.Showing you which mental maths facts are crucial to each stage.What do we mean by written?Rough translation L1 = Y1L2 = Y2L3 = Y4L4 = Y6 (nationally and we understand that all pupils are different)
7Why are we doing this?From your feedback after last year’s calculation night, more parents commented that they felt less comfortable practising subtraction with their children than addition.Also pupils (not just our pupils, pupils nationally) find subtraction harder than addition for any two given numbers.QuestionnairePast SATs analysis
8How do the children’s subtraction skills progress? Look at subtraction through the levels, how we teach it and how can you support it.
9Level 1 Understand subtraction as take away. Use practical and informal methods to subtract a one digit number from a one digit or two digit number8-5= 7-3= = – 8 =Subtract a multiple of 10 from any 2 digit number43-10= = =Find the difference by counting upBegin to recognise the inverse10-4 = = 10Solve simple one-step problemsRecord calculations using number sentences that include the appropriate symbols
10The story of 5 teddy bears 12345Once there were 5 teddy bears
19Level 1 Count backwards from any number to 20 Say the number that is one less than any number to 20Count back in 10sKnow by heart subtraction facts for numbers up to 5Recognise that subtraction has to be done in a particular orderCalculate by taking away objects or by counting back on number lineFind the difference by counting onWrite number sentences using symbolsUse objects, pictures and number sentences to answer a problemAnswer subtraction calculations using known factsUnderstand and use words that link to subtraction
20Break for Mental WorkYou are about to participate in a Year 1 Mental and Oral Starter (this usually lasts for around ten minutes at the beginning of every maths lesson, throughout school) which will help you with the skills needed for subtraction later!You will need your number fansBy Miss Chapman
21Year 2Subtract mentally a one digit number or a multiple of 10 from any two digit numberUse practical and informal written methods to subtract two digit numbersDerive and recall all addition and subtraction facts for each number to 10Recognise subtraction as the inverse of addition
22Level 2 Count back in equal steps of 2, 5 and 10 Partition numbers to 100 beyondDerive and recall all addition and subtraction facts for each number to at least 10, all pairs with totals to 20 and all pairs of multiples of 10 with totals up to 100Subtract by partitioning 56-6Subtract 10 from a two digit numberSubtract a multiple of 10 from a two digit numberSubtract by counting back or finding the difference by counting onSubtract the nearest multiple of 10 and adjustPartition the number to be subtracted 43-23Choose how to solve a problem and explain the methodRecord working out for subtraction problemUnderstand the relationship between subtraction and addition. Say the subtraction that matches an addition sentence visa versaExplain how they know to use subtraction to solve a problem
23Inverse Addition is the inverse of subtraction. Answers can be checked by using the inverse operation.We can solve ‘missing number’ problems by using the inverse method.25 – 19 = = = 251
24Can you turn these addition number sentences into subtractions? 6+2=89+7=1623+41=6439+22=618 – 2 = 616-7 = 9= 4161-39=22Can you make a different subtraction?
25This method can be used to check answers. 9+4=13Check an answer by turning it into a subtraction13-4=913-9=4or
31Subtraction – Level 2Using a blank number line to solve calculations and problems. Also known as finding the difference.74-27=Why count on and upwards?You could break up the +40 jump into jumps of ten until you become confident with the adding a multiple of ten.
33Try these 76 – 43 102 – 84 302 - 153 Use number line method. Start at the lowest number.Add on to the next multiple of ten.Then add to the ten below the final number.Then add on to the final number.Remember to COUNT ON NOT BACKTry it with decimals, it can become complicated.When using HTU you may wish to add on hundreds at some point
34SUBTRACTION – Mental Facts are Crucial Number line method- Must know (not be able to work out but know) your number bonds to ten4+6=? as well as 7+?=10 and 1+?=10Because you always add upto the next multiple of ten- You also need to know which multiple of ten comes next.e.g. 60 is the next multiple of ten after 54- You need to be able to add ten and small multiples of ten.Small multiples of ten upto 70You need to be able to work out the complements to ten quite quickly (2-3 seconds) or you lose your train of thought.
35Number Line Method Some pupils continue to use it into L3, 4, 5 Can become very complicated depending how efficiently it is used (especially with decimals)We don’t discourage pupils from using it if they are using it properly.We don’t mind them using it into L345 if they use it correctlyMiss out some steps it is quite goodUse every step for – and it has 10 calculations including one where you have to add 9 numbersThere are some shortcuts but these are unique to each question so difficult to be taught.
362nd break for Mental Work This Mental and Oral Starter helps develop place value.By Mrs AsvadiPlace value is needed for written column subtraction the 2 in 627 is not really a 2 but a 20
37Level 3 ExpectationsSubtract a two digit number from another (mentally)Subtract a three digit number from another (written)Subtract an amount of money from another (written)To solve 1 or 2 step problems where these calculations are neededNeed to be able to partition numbers (in their head and on paper)Need to know subtraction factsAt this stage subtraction becomes subtraction rather than adding onProblems may have a subtraction and an addition or otherwise for second part
38Level 3 Understand the value of each digit in a 3 digit number Partition to 100 beyond simple tens and onese.g = orKnow by heart subtraction facts for numbers up to 20Subtract 2 digit numbers using an efficient methodRecord the steps of subtraction methodCheck answer using inverseUse subtraction to solve problems
39Expanded decomposition As the children progress through level 3 AND have a thorough understanding of place value and partitioning, we start to teach them the more ‘standard methods’What is partitioning?All three things are key to understanding the method
40Try these765 – 543402 – 284Use the expanded decomposition method.It does work for decimals as well
41SUBTRACTION – Mental Facts are still Crucial Expanded Decomposition MethodMust be know the subtraction factsand othersMust be able to subtract a tens number from another (upto 200)and othersMust be able to subtract a hundreds number from anotherand others
42Subtraction – compact decomposition Efficient for all subtractions. Can get ‘messy’ if performing a calculation like
43Try these765 – 543402 – 28414.16 – Use the compact decomposition method.62.2 – 35.95
44SUBTRACTION – Mental Facts are Crucial Compact Decomposition MethodMust be know the subtraction facts to twentyand othersMust understand that in the example belowthey are really subtracting 30 from 70and not 3 from 7 (even though theyreally are subtracting 3 from 7!)
45Subtraction – compact decomposition PROs and CONsYou never have to do a subtraction that is harder than 18-9You must understand your ‘place value’ for the method to have any relevance to you or real lifeYou must know your number facts upto 20 – 10(any number to twenty subtract any numberupto ten)Can become ‘messy’ when you have athousands number on the top.Need to know less facts but understand more.
46(From L4 onwards the method must be efficient) Level 4 ExpectationsTo subtract thousands numbersTo subtract decimals to 2 decimal placesTo use subtraction as a part of wider problem solvingTo solve 1 or 2 step problems where these calculations are needed(From L4 onwards the method must be efficient)Need to have an understanding of decimals place valueEfficient (not putting 1034 dots and rubbing out 876 for 1034 – 876)
47Level 5 ExpectationsTo subtract one decimal from another, where the decimals do not have the same number of digits12.1 – – – 4.8To solve two or more step problems with these calculations.Eg 45.1 – 2.89
49Which method is best? Actually it depends on the question asked! Knowledge of number facts (addition and subtraction) underpins all calculations, no matter how large or involved (i.e. decimals) the numbers are.Although pupils have to have a deep understanding of maths to pick the right method based on the question/number type.We have had some pupils in the past that have done this.One reliable method AND KNOWLEDGE OF KEY NUMBER FACTS SHOULD SEE THEM ABLE TO ANSWER ANY QUESTION
50Thank you for taking part We hope it has been usefulThis PowerPoint will be placed on the school website.Please feel free to ask any questions, to members of staff, about the calculation strategies used.