Do schools teach (long) subtraction like this?

[MissusMaker]

DS is in year 2. I'm mostly consolidating his maths knowledge at the moment, using various worksheets/apps etc but sometimes we come across a new concept and I'm not sure if I'm teaching it in the right way... in this case we are talking about subtraction. He can do a subtraction such as say 55-22 by lining up the tens and ones, subtracting the ones column and then the tens column - he knew how to do this already. But then we came across problems such as 55 - 27 and I've been teaching him the way I was taught - you take from the tens column, reduce it by one and then add 'ten' to the ones column - so hard to explain but like this picture that I've just stolen off the net - is this how it's still taught?

Yes

That's how it was taught to my dd and ds. It's not how I was taught though

Yay! Thanks. I'd recently heard of 'chunking' but have no idea what is related to and was worried that I was doing this wrong 😂

I think - though it's a while since I saw it happening - that they put the numbers in different places. Watching my son do the way he'd been taught was definitely weird...

Might be worth explaining what it is you're actually doing? and prepare him for a slightly different notation method so that he doesn't get confused.

I used to teach in secondary and those that didn't know this method or used ridiculous box methods for adding were taught column methods in year 7. Much quicker so can focus on other things.
Some of the primary school methods the kids came in with were

Chunking is division and if you are over 35 you've probably never used it in school

Column subtraction is still taught but we used to borrow one from the tens -the language used now is exchange

The way you explain it is you exchange one of the tens and put it in the units (or ones) column

There are lots of worked examples on YouTube if you think watching it done may help 😊

I understand how to do it - and DS understands it the way I've explained it, I just wanted to check whether it was a good method to teach.

I'm 36 so slightly too old for chunking 😂😂😂

This is how we teach it. We "exchange" one of the tens for ten ones, which is why the tens column "reduces" and the ones column "increases".

I was taught the Equals Addition method in Scotland many years ago (I'm 46). DH was taught the Decomposition method in England (also 46)

Yes, that's fine for y2. Make sure that she understands why this is happening. Ask her to recreate the calculation with 1p and 10p coins or bundles of straws and explain it. Also I would expect y3s to be able to do any 2-digit addition or subtraction mentally without having to use the formal method, so work towards that too.

Please make sure you're not saying 'borrowing' - you're not going to give it back!

For your example you would say "We can't subtract 6 from 2, so let's exchange one TEN for ten ONES. So we now only have 6 TENS but we've got twelve ONES. 12 ONES subtract 6 ONES is 6 ONES, 6 TENS subtract 5 TENS is 1 TEN.

Yes, that’s used. I would teach exchange by using concrete materials first as it’s important that he truly understands why he’s carrying out the steps in a written method.

Is he using exchange to add in a written method already? Tens and ones sticks would normally be used (dienes) but you could use ten and one pence pieces to demonstrate. It sounds like you’re doing a great job with him.

And when I was taught it was 'borrow from the top, pay back at the bottom'. Completely unmathematical, but it worked.

That one of the methods in my picture above and was the way I was taught too

I learned (and now teach but using slightly different language as described above) subtraction using exchanging tens and ones.

In year two now, children are beginning to learn how the formal written method works by first using concrete materials, such as base ten. They're starting to understand what the digits in the number means and can partition them (split them into tens and ones) to subtract them. When they're confident with that they then move on to doing it pictorially, such as using sticks and dots like in my image.

At home I've demonstrated it with my y2 child using those small, single pieces of Lego as the ones and building them into towers of ten for the tens. Even if you've started using the formal written method, it doesn't hurt to use concrete materials alongside.

Yes but it's taught with concrete resources first where you 'exchange' one of the tens for ones. Then taught drawing pictures of what the numbers are. The digit form is the last step once they have a good grasp of it.

So children can actually see and understand what is happening. So many children I've taught in KS2 can do column method until the cows come home but have zero concept of what they're actually doing. Causes big problems down the line with limited understanding of place value. Never 'borrow': because you don't give it back!

Yes, this is how my DD yr 2 is being taught by school and us.

My year 2 daughter was working these out in her head and not able to show me her workings so I asked her teacher to clarify. She gave me three different ways they're being taught and none of them are this way! The other ways were so much harder to understand so now I'm confused about what I should teach her!

Does your dd's school provide parents with a copy of their calculation policy @worriedandannoyed? If so, ask for that. I'd try to avoid teaching her a method that's completely different from what she'd be learning at school because it could lead to confusion.

Yes we were given it after other parents asked. I've got a level maths and can't figure it out...

@worriedandannoyed same. My eldest has been shown so many long confusing ways to do a simple subtraction. He's doing it the way I was taught in school (like OPs way) and he's finding it much easier. He wrote his working down and and submitted it to the teacher only to have her message back saying he was to try it one of the other 4 ways she had shown...

When we teach this method it’s best to begin with manipulative. So I would set out dienes for example, to match the vertical subtraction.

When it came to a column that bridges ten, I’d get children to physically take ten from the column before and replace it with ten ones.

Then we can subtract.
We build it up step by step, moving on to written calculation alongside before finally moving straight to abstract.

Sorry that’s really unclear! But this is a good resource for virtual manipulatives if you felt you needed to give learning more grounding. mathsbot.com/manipulatives/blocks

I expect the other ‘confusing’ ways being taught lead up to supporting some sort of mental method. If children are taught column subtraction early on and don’t build up good mental methods (because ‘what’s the point the column method is easiest to do’ - which I agree it is) you can end up with y5 and y6 Children who default to column subtraction for everything even when a mental method would be better. For example 357-20 or 1000-999.
Also if they don’t understand what they are exchanging and why, they may come in to trouble with questions with a 0 on the top row, eg 307-128. They will carry directly from the 3 to the 7 with no understanding of why they can’t hop over the 0 in the middle. If they’ve used concrete apparatus’s in the early stages to understand exchanging, they’re more likely to see that you can’t turn a hundred in to ten ones.

We teach that method from Y3 and that was the same in my previous school too.