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Secondary education

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Original poster

When are fractions used in real life

73 replies

TeenTimesTwo · 05/02/2018 20:49

I was asked today by a y6 I'm helping when fractions are used in real life. I struggled to answer it.

Now, I know we often want basic use like 'a third off'.
I also obviously know about percentages, probability and ratios.

But when 'in real life' do you have to add fractions with different starting denominators, or multiply mixed numbers or whatever?

OP posts:
LIZS · 05/02/2018 20:52

Working out recipe quantities if written for 6 and you need to make it for 4.

Biggreygoose · 05/02/2018 20:56

Mixes. (Recipes, concrete, fuel etc etc)

If you fancy a splash on the gg's

In pretty much any engineering discipline.

VienneseFingers · 05/02/2018 20:56

Luckily I have never had to add fractions with different starting denominators or multiply mixed numbers as I can't remember how to and had actually forgotten it was even a thing.

VienneseFingers · 05/02/2018 20:57

And I cook a lot and bet on horses...

Slitherout · 05/02/2018 20:57

If you want to buy weed 😂

FATEdestiny · 05/02/2018 20:57

There is three quarters of a cake left. There are four children, plus Mum and Dad. How much cake each?

Original poster
TeenTimesTwo · 05/02/2018 20:58

I'm disallowing that LIZS as it's for ratios and too basic.
It's just 4/6 x the quantity Smile

I would like a harder use to help justify harder fractions work.

OP posts:
noblegiraffe · 05/02/2018 20:58

I use them all the time Grin

Yeah, not so much in 'real life' though. Probably one of those things that got used far more often back when we used imperial units and didn't have calculators. Old O-level papers are always full of horrible 'real life' fraction questions.

noblegiraffe · 05/02/2018 20:59

help justify harder fractions work

Ah, now you're in the territory of thinking it needs to be useful to be taught. Dangerous in a maths lesson!

FATEdestiny · 05/02/2018 21:01

We have 2 large pizzas cut into 12 plus 2 medium pizzas cut into 8. There are 10 of us. How can we all get a fair share?

Original poster
TeenTimesTwo · 05/02/2018 21:03

Fate - 3/4 div 6 - too easy.

Mixes - possibly, yes.
Betting, good example of something definitely.

I'm definitely not going to say when buying drugs! Shock

I did say harder maths, and formulae, which I guess includes engineering.

Nice ideas. Any more involving different denominators?

OP posts:
MarthaArthur · 05/02/2018 21:03

Measuring things in ratios. Or if she goes into mathmatic or science based jobs.

Biggreygoose · 05/02/2018 21:04

Noble is right though, fractions were far more relevant under the imperial system.

fruitpastille · 05/02/2018 21:05

It's hard to justify. Like long multiplication or division - I mean really who would do that on paper in real life? You need to have a sense of the value of the numbers and understand what the calculation does/is for so you realise when your calculator has made a mistake though.

Original poster
TeenTimesTwo · 05/02/2018 21:08

FATE I like that example, uses areas of circles too.

noble thinking it needs to be useful to be taught Ah I agree that could be dangerous. BUT it's nice if possible to show a real world application, and I couldn't think of one simple enough for an 11 yo off the top of my head and rather though there should be one.

OP posts:
Biggreygoose · 05/02/2018 21:09

When you have to be horrifically precise in a calculation and ain't got time to write that shit down.

Very much depends how you define 'real life's ...

Original poster
TeenTimesTwo · 05/02/2018 21:11

fruit I often(ish) do long multiplication or division as it's faster than getting a calculator!

There wasn't any attitude from the child ('why do I need to do this' moaning), just an interested question.

You'll need it for harder maths is a good enough answer.

OP posts:
liloland · 05/02/2018 21:12

Splitting the bill when dining with people who do that kind of thing.

Original poster
TeenTimesTwo · 05/02/2018 21:18

Surely not bill splitting, we're not on AIBU. Shock

Anyway, either divide by the number of people, or people pay for their own, or divide and adjust up and down a bit to allow for variation.

OP posts:
noblegiraffe · 05/02/2018 21:19

I've been banging on about using fractions to my Y10s recently, we've been doing completing the square and some are insisting on using decimals. I've been arguing that it's much easier to square a fraction than it is a decimal. I'll win that one eventually.

roguedad · 05/02/2018 21:20

You could wind the class up by having a project to see what

1+1/2+1/3+1/4+.... all the way adds up to.

Divergent series for junior school. Then you could get them to do the inverse squares sum on a calculator and appear godlike by getting then to see how close to Pi^2/6 they can get. Much more exciting than real life!

titchy · 05/02/2018 21:28

Estimating how much carpet you need to buy, converting currencies, sales shopping - is it really a bargain, converting imperial to metric, engineering - loads of examples from thickness of a steel to measuring traffic flow.

Original poster
TeenTimesTwo · 05/02/2018 21:31

rogue You could wind the class up
Not me. Not a teacher. Could never be a teacher. All those kids in one go? Couldn't cope.

OP posts:
ClaudiaWankleman · 05/02/2018 21:32

When doing taxes. You could easily be multiplying % and fractions in the same calculations as a bookkeeper.

Original poster
TeenTimesTwo · 05/02/2018 21:33

titchy Most of those are too easy, though the carpet one has legs if you turn it into tiles (iyswim)

Thank you all.

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