Pancakes Recipes

Proportion: Mixing: Making pancakes introduction

This is part of the Citizen Maths course available at https://www.jisc.ac.uk/citizen-maths

Original of the video here

Pancakes Recipes
Waffles Recipes
Pies Recipes
Cookies Recipes
Bread Recipes

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Video Transcription

this is a recipe for making pancakes and
you can see from the recipe that I have
the various ingredients that they need
to make 12 to 14 pancakes on a plain
flour eggs milk water butter and some
salt and the range in the amount of
pancakes really relates to the fact that
some people like their pancakes quite
thin and others like them thicker now
personally I prefer that our pancakes so
when I go to be using this recipe I’m
going to think about using the upper
limit the 14 pancakes as my measure of
the amount of pancakes that convenient
but I’m never going to eat 12 to 14
pancakes what I’m probably going to want
to make is two or three pancakes and so
how do I adjust the recipe ingredient
quantities in order to get the exact
amounts I need when I go to make two or
three pancakes we’re going to use a
spreadsheet to be able to do that so
that’s what we’re going to cover in the
next section I cook the ingredients for
the recipe into a spreadsheet and you
can see that for 12 to 14 pancakes I’ve
written dieing that I need 110 grams of
plain flour 2 eggs 75 milliliters of
water 50 grams of butter a pinch of salt
and 200 milliliters of milk but as I
said earlier I’m not going to eat 12 to
14 pancakes I’m gonna 8/8 two or three
so we’re going to look at how do we do
the calculation for that reduced amount
of pancakes so the first thing you do
when you’re using a spreadsheet after
you’ve put your mind soon is to click on
the cell where you’re going to do the
calculation so I’m going to click here
and to tell the spreadsheet that this is
a calculation you use the equals sign so
having entered equals I can I then start
to do the calculation like I’m going to
look at making two pancakes and I want
the thinner pancakes so I’m going to
look at the upper limit of the original
recipe which was 14 pancakes so I’m
going to do two pancakes
well as a fraction we’re only going to
do two divided by four and you can see
here that the divided symbol on a
spreadsheet is the slash button okay so
we’ve got 2 divided by
that’s the fraction of the original
quantities of the recipe that I’m
actually going to be making for my
reduced amount of pancakes so two
divided by fourteen and then what I need
to do is to calculate it for each of the
ingredients so what I want is that
fraction x now the x button is the star
so two divided by fourteen times and in
this case we’re going to start by
looking at the flour so click on the
sale it has the flour and hit enter and
what that gives me is a calculation of
the amount of flour that I’ll need in
order to make two pancakes
so it’s fifteen point seven or lots of
digits after that now what I’m going to
measure that right obviously I don’t
really want all the numbers after the
decimal point so it makes sense for me
to be able to run that and remember when
we’re writing a decimal you look at the
value after the decimal point if we’re
writing it to a whole number and if it’s
five or more we’re going to be rounding
up so in this case that decimal is
approximately 16 to the nearest gram so
if I’m making this on line two pancakes
I’m going to need 16 grams of flour
similarly I can repeat the same process
for eggs water love etc so remember from
before to put your equal sign and then
you’ve got two divided by fourteen
because that’s the fraction of the
original like that I’m going to be
making and then times it by the value
that’s in the sale that we’re looking to
calculate it so in this case the amount
of eggs 9 that seems strange doesn’t
matter we’re going to calculate
calculates that we’re going to need not
point to yet five eggs what does that
actually mean well it means that we
don’t need a whole egg we’re going to
need a fraction of a whole egg and so
you can do that on a variety of ways you
could crack a full egg put it into a
measuring jug and then measure whatever
quantity isn’t it currently so if it
works like to be ten milliliters or
something like that you’re going to find
not point two eight five seven times
that and then run that to the nearest
milliliter so just remember that that’s
what that actually means okay
we could work our way down the
spreadsheet then again so we’ve got a
fraction of 214th
and then we’re going to multiply that by
what’s in this cell which represents the
amount of water in the recipe and when I
hit enter and going to need
approximately 1100 liters of water and
again just working our way down we’ve
got two 14 and I could be multiplying
but they might have butter in the
original recipe and when I calculate
that that tells me that i roughly need
seven grams of butter now what happens
when we get to a pinch of salt
remember the calculation is 214 of the
original length so it’s two fourteenth’s
of a pinch and that’s really
mathematically seem to make sense so
basically we’re going to want a much
smaller pinch of salt for our
ingredients okay so we’re looking at a
bite as seven to fourteen is a seventh
and I’m not going to do the calculation
for a milk we’re going to come back to
that in a little moment using the
scratch app I can check the calculations
that I’ve just done on the spreadsheet
I’m going to use the bars to represent
the different quantities the yellow bar
is going to represent the number of
pancakes and I am the original recipe
it said stated that we could make 12 to
14 pancakes and because I like my
pancakes then I’m going to use the upper
ends of that range which is 14 so I’m
going to use the recipe ingredients from
the original recipe to make 14 pancakes
and the pink bar then is going to
represent the quantity of ingredients in
the original recipe we can look at those
one at a time so to begin you click on
the green flag and the yellow as we said
will represent the number of pancakes
which is 14 now I come to the problem of
the pink bar now the pink bar I’m going
to look at the amount of flour that I’m
going to need in the recipe and it’s 110
grams but you can see that the quantity
that I’m able to enter for a pink has to
be between 0 and 57 so just
professionally I’m going to put 56 and
you can see that what the problem is
that 56 fills nearly the the complete
length of the app screen so what I need
to do is to reduce the length of the
bar that’s represented by yellow which
will in turn reduce the length of the
side of the bar that’s represented by
pink so to do that I’m simply going to
hit the down arrow and you can see that
the yellow bar is getting reduced in
size and once I’ve got it reduced enough
then click on the reset button and now
you can see it resets back to 30 but now
we have the yellow bar much smaller I’m
going to then click the green flag and
enter it again so now you’ve got 14
pancakes represented by the yellow bar
and you can see you know that the pink
bar has a bigger range so I can put in
my hundred and ten grams which would
represent the amount of flour I need
okay we’re not going to be making 14
pancakes I want to make just find out
what ingredients I’ll need for two
pancakes so looking at the flour if I
just click on the yellow bar and reduce
the amount of pancakes down to two and
once I’ve got that to hit the spacebar
and that allows me to see that I’ll need
16 grams of flour now you can repeat
that process for each of the ingredients
in the original recipe to work out the
amount that you’ll need for two pancakes
as opposed to the original 14 the
original pancake recipe was for 12 to 14
pancakes and I don’t want to make 12 to
14 pancakes I only want to make 2
pancakes and because I like them thinner
I’m going to be supplying the 14
pancakes in the original recipe so what
I need to do is to look at what 2
pancakes is as a fraction of the
original recipe so because I’m making
the thinner pancakes I’m going to write
2 over 14 and when we cancel that dying
that work site at 1/7 so I’m going to be
looking at 1/7 of the original alights
and the recipe now let’s look at flour
first of all in the original recipe the
amount of flour needed was a hundred and
ten grams but because I’m not making 14
pancakes and when you making 2 pancakes
I need to work out 1/7 of that so let’s
do that calculation 1/7 of a hundred and
10 grams I’m going to use a calculator
for this part so
let’s just bring the calculator in and
work right so we’ve got 110 grams and we
want 1/7 to find 1/7 we’re going to be
dividing by 7 so 110 divided by 7 and
that gives us fifteen point seven one so
let’s write that dying 15 point seven
one and that rains up to 16 grams so
when we’re in the original recipe we
needed 110 grams of flour to make 14
pancakes and for my recipe I’m going to
need 16 grams of flour to make 2
pancakes

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