Who needs ratios and fractions? Well, you need ratios and fractions. You use them all the time! Give me half a minute. Can I have half rice, half chips? A third of my class are halfwits - which is the same as saying half of my class are third wits, mathematically speaking. One place you'll definitely need your ratios and fractions though, is in the kitchen.
So here's the deal. I've got a pile of mince the size of my head. That's a lot of mince. So I'm going to have some friends round for dinner tonight. 20 people are coming. Yeah, I've got 20 friends. 16 are from an agency but the point is I've decided to cook a big old pot of chilli for 20. What am I going to need to make chilli for 20? Well, I think the first thing I'm going to need is a bit of help…
Hello, Emili!
Hi, Sanjeev.
How are you?
I'm very well, thanks.
Good. Is maths something you would use in your everyday professional life?
Absolutely! Every single day, whether I realise I'm doing it or not, I'm always using maths.
So what's the most you've ever catered for?
Oh, I've catered for anything from one person to 1,001!
Cool, so you could cope with 20.
I think I can cope with 20. All you need is confidence in your recipe and some maths!
Well, I've got my mum's secret chilli recipe here although I clearly got it from a website. Rumbled, Mum!
But this recipe's only for four people.
Oh, and we're catering for 20. Ah, so oh, right, so what now then?
Well, I guess we scale up from four to 20.
So what we're doing then is multiplying everything by five.
Yep.
OK. I think I can cope with that. So it's 500 grams of mince times five is 2,500. 600 grams chopped onions. OK, so two tins of tomatoes.
OK, so that's easy.
Two times five.
Ten!
That's it, you got it!
Ten tins of tomatoes, OK.
Ah, right, now. That wee guy's a fraction. One-and-a-third cans of kidney beans.
A bit more tricky.
Yeah, why don't… What we could do, we could empty a can of kidney beans, count them and times that by five.
That's crazy talk. Are you scared of a little fraction?
I'm not scared of fractions!
Put in six and a bit.
Six and a bit? OK.
Red peppers.
Red peppers. Ten cloves of garlic. And one stock cube times five. Five stock cubes. OK, next up is the extra-hot chilli paste.
And that's another fraction.
Yeah, this is crucial because I get this wrong and we're spending the night in A&E ha-ha!
Argh!
So five times 2.5. So that's 12.5 teaspoons of extra-hot chilli paste. That's a lot of chilli paste isn't it?
Well, 20 is a lot of people.
Fair enough OK.
When it comes to cooking it's not just recipe and technique. There's maths in that pot.
Top kitchen work Emili. Er, that's the food in good shape, the chilli bubbling away there like er two pots of mince with other stuff in it. Hopefully in the right ratio. Er, but what about drinks for my wee soiree? Well, er, funny you should ask.
Well, I'm a sophisticated kind of guy. Kind of know minor royalty. I eat fruit you probably never even heard of. So I want a sophisticated drink. I'm going for a non-alcoholic cocktail that's one I invented myself. I call it the Jazzy Handbag. It's four parts cola, two parts orange juice, one part chicken stock. Mmm!
So I'm thinking a litre of this taste sensation per guest. 20 guests - and er not forgetting myself that's 21 litres of Jazzy Handbag. Who said I can't throw a party? Ahhhh! That's perfection. The chicken really dances on the tongue. So all we need now is guests.
Now as you can see I've invited them at 7.30 on Saturday and the time now is…quarter to, that's 15 minutes to nine on…Friday. Do you like chilli?
Video summary
Sanjeev Kohli has 20 friends coming round for dinner, but his mum’s recipe is only for four.
He needs to change each quantity and be able to scale up each ingredient.
Some of them have fractions, so this can get a bit tricky.
This clip is from the series Who Needs Maths?
Teacher Notes
This could be used to illustrate practical uses of ratio in changing recipes.
Students can then have a go at completing Sanjeev’s party menu, changing other recipes and thinking about different calculation strategies for more challenging numbers of guests or quantities of ingredients.
For homework they can then ask parents/carers for their favourite recipe, and scale it up to feed the whole class.
This clip is relevant for teaching maths at Key Stage 3 and Third/Fourth Level in Scotland.
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