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Education

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Original poster

Maths teachers, what is this called ?

96 replies

fastweb · 05/10/2011 21:23

I've flicked ahead in son's maths textbook to see whats coming up next to aviod being caught on the hop.(again)

What would you call this in English ? (it's a quick video, cos I don't know how to upload pics)

A literal translation suggests "absolute rational numbers", but when I googled that it didn't look the same at all.

freemathdictionary.com/aa/absolute-rational-number/

OP posts:

Organa · 13/10/2011 12:42

If i were doing that equation, I'd think of it as ratios e.g. 3:1 So the first part is 3/4 and the last part is 1/4. It looks like just a big attempt at teaching the children to learn to solve fractions by finding the common denominator.

The layout is unusual though (and I got all the way through a degree in maths without ever coming up against a question like that!)

PS I am not a maths teacher either

Original poster

fastweb · 13/10/2011 12:47

and I got all the way through a degree in maths without ever coming up against a question like that

That does not bode well for me teaching my son to do them.

I failed my maths O level.

The colon I think stands for divide, it's the usual symbol at school here, but would not put it past the authors having bunging ratios in the middle of double decker fractions just for the sadistic thrill of it.

OP posts:

Organa · 13/10/2011 12:55

doesn't / mean "divide"?

I'd look at it this way... its more than likely a bit of trivia dreamed up by whoever wrote those problems. It may even be a typo. Your son will do well if he's good whether or not he knows what that symbol means because its use is so rare it is incredibly unlikely that it will ever turn up in an exam question ever (unless he's training to be a bookie)

Original poster

fastweb · 13/10/2011 13:04

They use both here, but colon was more common at elementary school than \

Ohhh, typo, maybe those pages got accidentally put in his book instead of a much higher level book.

OP posts:

Organa · 13/10/2011 13:35

how old is your son? from what i can see it looks complicated because its so big but the problems are actually made up of lots of little problems that are really just about fractions. Maybe the idea is to teach him to solve it one step at a time?

Original poster

fastweb · 13/10/2011 14:26

He is just 11.

But one of the younger ones in class, so I'd say the average age was 11 going on 12.

OP posts:

noblegiraffe · 14/10/2011 12:14

I teach some Polish girls who also use a colon for division. If you think about it, our divide sign is just the colon with a line through the middle (it's meant to represent a fraction).

Fastweb, I think your DS is very lucky to have you as his mum!

pixieandpoxie · 14/10/2011 14:02

Here in Germany, we use : for division and a dot in the middle for multiplication (like a decimal point). It is very confusing to get used to but actually more mathematically correct. x and / would only be used later on for matrices.

Organa · 14/10/2011 14:23

the dot in middle instead of the X is what is used to denote multiplication in British university maths too. I think its also used in the later years at school.

i don't recognise the : though, unless to denote a ratio.

pixieandpoxie · 14/10/2011 14:28

I know. It took me ages but I do remember vaguely, all those years ago, one of my lecturers wittering about it. The maths here has my brain in a spin most of the time but getting there. Really feel for OP. My DD (12) did questions like this last year too.

pixieandpoxie · 14/10/2011 15:54

Sorry, I meant the dot for multiplication was more mathematically correct. I've just asked dd why they use a colon and she said it comes from the way they teach division. They actually teach it as a ratio so the colon is the obvious symbol.

noblegiraffe · 14/10/2011 16:01

But it's not a ratio! 1 divided by 2 is not the same as 1:2. In the fraction the quantity is split into two parts; in the ratio, it it split into 3.

Organa · 14/10/2011 16:05

so if you see the question 1:2 then the answer is either 0.5 or 0.3333

Obviously one is right and one is wrong, so the OP will need to find out which when the curriculum gets round to that bit of the syllabus. All I am saying is that if I was doing a maths exam paper and came against that question. So there was no opportunity to ask then I'd guess it was a ratio and answer 0.333.

pixieandpoxie · 14/10/2011 16:12

I totally agree. We only moved here 2 years ago so dcs got a quick rundown on the way they do things. Being the inquisitive sort dd asked her maths teacher and he told her that ratios and fractions were related so thats why they used it.

noblegiraffe · 14/10/2011 16:16

If you do those fraction questions in the OP and do : as division, the fractions work out nicely. A ratio in the middle of a calculation doesn't make any sense. 1:2 doesn't mean 0.333, it means 'for every one of something, you have two of something else'; it is a statement rather than an operation.

IShallWearMidnight · 14/10/2011 16:17

someone on here used Interhigh (I think) for her DS, certainly one of the online schools. I have a feeling it was AMumInScotland, but a search through the home ed board woudl probably get you there. She was pretty happy with how it all went as I recall.

noblegiraffe · 14/10/2011 16:18

he told her that ratios and fractions were related

They are, but I'd really rather not confuse the kids any more than they are!

If a class contains boys and girls in the ratio 2:3, that means that 2/5ths of the class are boys, not 2/3rds! The amount of times I've seen this mistake....

pixieandpoxie · 14/10/2011 16:23

If my dcs saw 1:2 in a question they would always divide. The only other time we have come across colons is scaling on maps. They haven't actually done ratios as a topic yet.

Original poster

fastweb · 14/10/2011 18:04

noblegiraffe

That was a lovely thing to say, thank you.

Are you sure I can't talk you into being cloned so you can come and teach over here too?

I'll pop over to the HE board and see if I can find any other inter high users.

in better news the first English test results came back today.

A 10, and 9.5 and a 9

He is both delighted he got high marks, and miffed he came third.

But that is his own fault for not listening to me about taking care with his spelling, (three daft spelling mistakes cost him three perfect tens.... Therteen, Ganuary and Wensday.) I appear to be paying SpellingCity for the sake of giving my creditcard an occasional airing. But have a feeling it is to become rather more popular with him for the foreseeable future.

OP posts:

pnod · 15/10/2011 12:26

I'm certain the colon refers to a division. I think a lot of European countries use this kind of notation. Like ninani says, there wouldn't be enough space in the exercise book to write it as a fraction.

My kids go to school in Germany. They also use a colon to express a division. It makes it a lot easier to type. I find it a bit odd that the Italien textbook uses the x as a mulitplication symbol. In Germany they use a dot ( a comma is used as a decimal separator). Personally, I prefer this system. I find it easier to read.

BTW a semicolon would also be used here to denote a ratio.

Anyway, if your DS can manage to do those exercises - he'll be pretty good at fractions :-)

noblegiraffe · 15/10/2011 14:06

I love Italy (omg the food) but I think I would go insane trying to teach over there in such a backwards system.

And it is backwards, it's not just different. There is lots of research out there about how to teach effectively. Some of it is decades old. And none of it recommends that the best way to teach maths is to set large swathes of it as 'self-study', or to dictate it.

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