A quick maths question - would be really grateful!

[Creole]

Please help me with this, my Yr3 DS seem to think his method is right and won't listen to a word I say:

By how many mm is a strip measuring 25cm longer than a strip measuring 220mm?

Ignore me

It's 30mm

NB this isn't maths it's english comprehension

The language of maths is a whole area in itself and should be taught as part of maths.

'how many ... longer than...' is a common maths question in information handling. Children should be taught to recognise it and understand that the term means they have to subtract.

By how many mm is X longer than Y

30mm

Don't see the confusion myself....

I got confused by

"a strip measuring 25cm longer than a strip measuring 220mm"

I think they are pointydog.I went to a talk at my dd's primary school recently on how they teach maths and english and they did mention the language that is used.
It was 9 years too late for me really as I could have done with it when ds started not now when dd is in yr 6.

Key word is BY

Answer is 30 mm

Bit baffled by KatyMac though (What ARE you doing? )

Ooops missed the last few posts. Get you now Katy

Ooops missed the last few posts. Get you now Katy

30mm, or 3cm.

I also see this a test of English comprehension!

If you were to re-write the question to make it clearer to your DS you could say:

ORIGINAL PROBLEM: "By how many mm is a strip measuring 25cm longer than a strip measuring 220mm?"

1. There are 2 strips. The first strip is 25cm long. The second strip is 22cm long. How much longer is the first strip, compared to the second strip (or BY HOW MUCH LONGER is the first strip, compared to the second strip?)? Answer: 3cm

1. There are 2 strips. The first strip is 250mm long. The second strip is 220mm long. How much longer is the first strip, compared to the second strip (or BY HOW MUCH LONGER is the first strip, compared to the second strip?)? Answer: 30mm.

Or maybe this is just more confusing!

I agree that the tricky concept is BY HOW MUCH LONGER. I would further prep him for similarly-worded questions with a 'BY HOW MUCH SHORTER IS x than y?'...

Clear as muck. Sorry.....!

There was no need to ask "By how many millimeters...". It could just as well have asked "How much longer is..."

The answer would have been 30 mm or 3 cm. Same thing.

I assume that because they specifically asked for mms then the answer of 3 cm would be wrong.

I can understand your DS getting confused by 'a strip measuring 25cm longer than a strip measuring 220mm' and coming up with 470mm but how does the 'By how many mm is ...' fit with the rest of his sentence? (answer: it doesn't!)

OMG! Can't believe you are still debating this....it seems the question is a bit too ambiguos(sp) then. No wonder my Ds had problems with it. He was really adamant that it was 470, hence the reason why I posted...

Gosh, this is yr3 maths (well, he's in the higher group), but us parents had a problem with it, God help the average 7/8 year old!

As it is Year 3 I should say its 30mm and a badly worded question.Top tip -look out for rulers which show mm on 1 side and cm on the other -more useful than inches and cm

My dd1 is not a genius when it comes to maths sadly, she can get by but what confuses her the most is the way they word the questions. If it was just a straight forward question, how much longer is x than y she'd be fine, but because they put in these long convoluted questions she gets all muddled and stressed out, it really annoys me, why not keep it simple.