Mr Hughes & Mr Murray Year 3

First of all – 10 questions whiteboards ready!

What is 207 minus 134? What is 207 subtract 134? Can you decrease 207 by 134? What is 134 less than 207? What is the difference between 207 and 134?

What is the remainder when 134 blocks are removed from a pile containing 207? I have £207 and spend £134, how much do I have left? I had 207 books and lost 134 of them, how many does this leave? What is 207 take away 134? From 134 how many more to make 207?

Subtraction Vocabulary You have just seen 10 different ways of asking the question There are other pieces of subtraction vocabulary as well The answer was 73 You don’t always see the word subtraction when you have to subtract.

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.

How do the children’s subtraction skills progress?

Finding the difference between 2 numbers

The difference is 5. The red tower has 5 more blocks What is the difference between 2 and 7?

What is the difference between 4 and 10? The difference is 6 There are 6 more yellow blocks

Level 1 Count backwards from any number to 20 Say the number that is one less than any number to 20 Count back in 10s Know by heart subtraction facts for numbers up to 5 Recognise that subtraction has to be done in a particular order Calculate by taking away objects or by counting back on number line Find the difference by counting on Write number sentences using symbols Use objects, pictures and number sentences to answer a problem Answer subtraction calculations using known facts Understand and use words that link to subtraction

Break for Mental Work You 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 fans By Miss Chapman

Year 2 Subtract mentally a one digit number or a multiple of 10 from any two digit number Use practical and informal written methods to subtract two digit numbers Derive and recall all addition and subtraction facts for each number to 10 Recognise subtraction as the inverse of addition

Level 2 Count back in equal steps of 2, 5 and 10 Partition numbers to 100 beyond Derive 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 100 Subtract by partitioning 56-6 Subtract 10 from a two digit number Subtract a multiple of 10 from a two digit number Subtract by counting back or finding the difference by counting on Subtract the nearest multiple of 10 and adjust Partition the number to be subtracted Choose how to solve a problem and explain the method Record working out for subtraction problem Understand the relationship between subtraction and addition. Say the subtraction that matches an addition sentence visa versa Explain how they know to use subtraction to solve a problem

Inverse 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 = = = 25

Can you turn these addition number sentences into subtractions? 6+2=8 9+7= = =61 8 – 2 = = = =22 Can you make a different subtraction?

This method can be used to check answers. 9+4=13 Check an answer by turning it into a subtraction 13-4=9 or 13-9= 4

Solve a missing number problem +7=15

The children use the numbers they have been given! +7=15 It is an addition, so start at the end and turn it into a subtraction… 15-7= 8 8

Subtract the nearest multiple of 10 and adjust 52 – 9 =

534 2 First subtract ten. But that’s one too many, so now add one back. Now you’ve subtracted 9 from 52 by subtracting ten then adding 1 back. Subtract the nearest multiple of 10 and adjust

Subtraction – Level 2 Using a blank number line to solve calculations and problems. Also known as finding the difference =

53 – 25 = Lets find the difference! = = 8 53

Try these 76 – – 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 BACK Try it with decimals, it can become complicated.

SUBTRACTION – Mental Facts are Crucial Number line method - Must know (not be able to work out but know) your number bonds to ten 4+6=? as well as 7+?=10 and 1+?=10 Because 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.

Number 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.