hey my name is kayleigh and this lesson is introducing ratios
have you ever sorted colored blocks so you have a bunch of colored building
blocks spread all over the floor and you decide to put all the red pieces
together and all the green pieces together and all the blue pieces
together let's do it together using a game made by ck-12 here we are in the
ck-12 interactive game and the directions are up here they say sort the
shapes by dragging them into the boxes that match their color and after you
sort the shapes fill in the blanks to complete the ratio sentences so let's
get started here I'm going to start by putting all of the red blocks into that
red rectangle at the bottom we have some fun shapes and we got one more here and
my blue box I'm gonna put my blue blocks in the blue rectangle like that and
finally my green blocks and now some questions so it says the number of red
blocks two blue blocks is and then I have to fill in the blanks so the first
thing it's asking me to find is the red block so I'm going to count how many red
blocks 1 2 3 4 5 I'm gonna put 5 into this first answer box here which
represents the red blocks and blue ball locks let's count them 1 2 3 4 so I'm
going to put a 4 in this answer box to represent the blue ones and it says the
number of blue blocks two green blocks is so now I'm comparing this many blocks
to this mini blocks and blue we already counted those we
know is four and green one two three four also is four and finally the number
of green blocks two red blocks is so I've already counted my green blocks I'm
gonna put those in the first answer box here it's four and the number of red
blocks I've already counted that is five put that in that one so now we've
completed all of the answers what we just did was find a relationship between
different things this is called a ratio a ratio is a relationship between two or
more quantities remember a quantity is an amount or how many of something you
have you can also use ratios when we work with words using ratios to solve
word word problems happen all the time when you're baking Sally wants to bake a
double layer cake the recipe says for every two cups of flour use one stick of
butter here is the recipe for one layer cake but Sally needs to double the
recipe to make the cake double layer since Sally has to double the recipe she
will need to use four cups of flour not the original two cups from the one layer
recipe but the original recipe says for every two cups of flour use one stick of
butter so if she used four cups of flour she will need to use two sticks of
butter what words in the phrase for every two
cups of flour use one stick of butter helped us find our answer
that's right the for every a good way to know that you're working with ratios is
to keep an eye out for special phrases for every
for each and per all signal that there is a relationship between quantities
let's practice identifying ratios with these phrases what do these phrases tell
you about the ratio of legs to spiders for each spider there are eight legs
there are eight legs per spider there are eight legs for every spider the
ratio is eight to one there is another way to write ratios it looks like this
where we say two when we see the colon it's important to note that the order
you write a ratio is very Super Duper important let's use a tape diagram to
practice writing out ratios so here we are in another ck-12
game and we're gonna write the ratio of blue ball blocks to red blocks and we're
going to write the number and these answer boxes here so this ratio is with
the blue question mark is the number of blue blocks one two so I'll put a two in
there two red blocks remember we say two when we see the colon is one two three
four five and we're right let's do another one this ratio is see if the
blue question mark goes first that means we're talking about blue
blocks one two three four four blue blocks colon means to the number of red
blocks I have a red question mark one two three four five we did it with
ratios may seem new to you right now you've probably been doing them for a
while a ratio can also be written as a fraction let's think back to our spider
ratio how do you think we could write our rice ratio for spiders to legs as a
fraction remember the ratio of legs two spiders is eight to one we can write
it as a fraction looks like eight over one or we can say the ratio of spiders
to legs is one to eight and can be written as a
fraction that looks like one over eight notice that even when we use fractions
to represent ratios the order of the numbers is still very important
the first number goes as the numerator of the fraction and the second number
goes as the denominator of the fraction
that completes your intro to ratios you did a great job keep studying ratios by
playing our games and completing the activities have fun and remember to
always be clever