Year 2 methods for subtraction?

[AChickenCalledKorma]

Hoping some teachers or parents of Year 2 children can help. What methods are used in Year 2, for subtraction of two digit numbers? DD2 is Yr 2 and has brought home about 30 maths problems for homework. She's supposed to explain her method to me, but she's stumbling on all the subtractions and doesn't seem to have a clue how to tackle them, beyond counting on her fingers. Which isn't very practical when you are subtracting two-digit numbers!

I'm sure she's been given methods to use, and is just having a bit of a moment. But anything I suggest is meeting blank looks.

Bouncing back on a number line is the method which seemed to work best for mine at that age.

So - draw a number line putting the number you are subtracting from one the left -then 'bounce back' with big bounces for tens first and then smaller bounces for the units. If it helps then

So for the sum 54-51 the line should look a bit like this:

54 _ __3
UUUUU u

Does that help?

Arse - formatting mucked my number line up

Will try again...

Yes, that helps! Different size bounces for 10s and 1s makes sense.

54 .......... ....3
...........UUUUU......u..

Ignore the dots

My daughter uses a number square and an abacus, (not both at the same time.)

We teach two methods for subtraction:

1- finding the difference. This would be the best method for two close numbers.

+1 +1 +1

/ / /

_
51 52 53 54

2. subtract in tens and units

3 4 14 24 34 44 54
__
\/\/\/\/\/\/
-1 -10 -10 -10 -10 -10

The larger number should always be to the right of the smaller number- this is how all number lines work! Only exception is with negative numbers.

...+1......+1........+1
/--/--/---


51.....52...... 53 ......54

2. subtract in tens and units

3....4.....14.......24......34..........44......54
_
\/\/\/\/\/\_/
-1.....-10.....-10.....-10.....-10.......-10

A bit better! Ignore dots as well.

STOP!

Wrong way, subtraction should be done R-L!

Thanks all. Good to know that 10s and units do feature - DD2 was looking very blank when I mentioned those. Maybe she was just tired! Will try again tomorrow (40 problems for HW, only 10 completed . Not sure why she's got so many this week - much more than usual which made me think she was supposed to be finding them quite straightforward ...)

At what age are they expected to do double digit subtraction in their heads?

That's quite an advanced skill. We teach 54-51 as counting on from 51 to 54, so I'd expect level 2s to be able to do that.

It is more difficult if they have to cross over a tens barrier. Something like 86- 31... I would expect that of a level 2 child. Something like 71 - 48 more like a level 3.

We teach 86 - 31 as either counting on, or most children do 80-60 then 6-1. Works as long as it doesn't cross the 10 barrier.

juniper that's really helpful. DD2's mid year report had her on level 2A and I'm guessing this homework might have been pitched at level 3. Either that or her teacher had a mad moment, because it was much harder than anything else she's brought home!