who the chuff thought teaching division through chunking was a good idea???

[sausagesandwich34]

it's stupid, long winded and confusing

that is all!

[Alliwantisaroomsomewhere]

What is chunking? (Or more precisely: what the fuck is chunking?)

[pointyfangs]

I must disagree. It let you do sums that would normally require long division on paper in your head. In under a minute. I was an unbeliever too, until I had it explained to me by DD1's maths teacher, and I am now a complete convert.

[FromEsme]

It's the only way I can do it.

[cece]

It is actually much easier once you can do it!

[pointyfangs]

The example we did:

431 school children are going on a school trip, on coaches. Each coach holds 38 children. How many coaches does the school need.

So you start with 38 x 10 = 380

431 - 380 = 51

You can fit another single 38 into that, leaving 51 - 38 = 13.

So you need 10=1 = 11 coaches, plus one additional coach for the remaining 13 children making 12 coaches in all.

[pointyfangs]

10+1, even.

[Feenie]

Except when discussing the remaining 13 children, many children will say eagerly 'they could come on our bus!' thereby spectacularly missing the point.

[lljkk]

I like chunking, I find it quite intuitive. So much better than rote long division like I was taught.

[yellowvan]

chunking is fab, except when it is taught too soon, or badly, to kids who dont understand the relationship between division and subtraction.

[Waitforit]

Or suggest that the remaining children will just have to stay at school!

[Houseworkprocrastinator]

I have never heard of or been taught chunking but pointy's example would be exactly how I would work it out anyway so I would say it is intuitive.

[pointyfangs]

Good point, Feenie. And of course there's always the luggage compartment...

On this occasion the teacher was talking to groups of parents only, so that may have influenced his choice of example. And he may indeed have been thinking in terms of the luggage department, he used to accompany all the school trips!

[CecilyP]

The person who thought it was a good idea was the one who met lots of people who struggled with long division because they did not know their 38 x table.

[TwllBach]

Can I ask... In the example above, why do you multiply 38 by ten?

[pudding25]

I teach chunking. It is fab. Once the kids get it, it makes division so much easier.

[Lougle]

TwllBach because everyone knows that to multiply by 10 you simply add a 0 to the end, so 38 becomes 380, and you know that 380 is less than 431. That means that you only have to worry about the remaining 51.

[pointyfangs]

What lougle said. It's all about using the easy multiples - 10, 2, 5 - and using them to make an easy number which is smaller than the original number (or the number you are left with after stage 1).

A confounding factor is that children are often taught to repeat the same step many times (because that is seen as easier), whereas as an adult you would take the identical steps all together in one bite. Once you've got past that though, it really is a great method of working with very large numbers for which you would not have the times tables readily to hand in your head.

[sausagesandwich34]

but the way DD has been told to do it, she can mange but I still think my way is easier but there seem to be lots of steps

for example....

346/3
100x3=300
15x3=45 (which she worked out by 10x3 and then counting on in 3s on her fingers)
100+15=115 r1

eh???
that's not simple!!!

[Lougle]

Well how would you do it in your head?

I love long division on paper, personally. But in my head, I'm likely to say to myself:

3 100s is 300, 3 15s is 45 and one remaining.

The only difference to your DD is that I know my 15 times table sufficiently, or conversely, I know my 3 times table to over 15. Your DD clearly only knows her 3 times table to 10, so had to count on after 10.

She could have broken it down further, if she wanted to:

100 x3= 300
10 x 3= 30
5 x 3 = 15

100+10+5 =115 with one remaining.

[sausagesandwich34]

I asked if she could and she said no, she had to do 46 in one chunk and they get told off if they use the wrong method

I would have done

3/3 =1
4/3 =1, carry the 1
16/3 =5

answer 115 r1

[Lougle]

Annnd if you look at what we do in long division:


3|346

I do the old-fashioned method:

3s into 3 goes 1

1
3|346

3s into 4 goes 1 with one remaining
11
3|346

3s into 16 goes 5 with one remaining

115 _
3|346

then I'd be putting my decimal point in and getting .33 recurring (but I won't type all that)

That's the same as 115 with 1 remaining.

[mnistooaddictive]

Yes, maths teachers have invented a method of division that is very difficult and they insist in teaching it just to confuse as many children as possible

It works for many children who struggle with long division. We teach it because it works.

[pointyfangs]

And the way lougle has just broken it down is how your DD should have learned it at her age, OP. The idea is to use only the 'easy' tables wherever possible - 2, 10 and 5. As an adult you can then use the method with more difficult tables and have it come in very handy.

Having said that, the example you have chosen lends itself particularly well to the long division or 'bus shelter' method - but most division does not.

[stargirl1701]

Suits some kids, not others. Kinda why we teach more than one method.

[Lougle]

Yes, but the argument is that the method we use doesn't actually show any reason for the answer.

We say '3s into 3 goes 1'

but that shows no understanding that what we are actually saying is:

3s into 300 is 100.
We say '3s into 4 goes 1 with one remaining'

but that shows no understanding that actually we are saying:

3s into 40 is 13 (39) with one remaining

then when we do the '3s into 16 goes 1 with 1 remaining' the actual truth is:

3s into 7 goes 2 (6) with 1 remaining.

So, adding up our real totals, we get:

100 + 13 + 2 = 115 with 1 remaining.

Not the 1/1/5 that we think we get.

So, in short, we can use the method, and it gets the right answer, but doesn't show understanding.