1. Exploring Ratios

2. On her bird watching expedition, Cassie spotted 6 robins and 3 bluebirds sitting on a fence.
Here are some ways she compared the birds:
Number of robins compared to number of bluebirds:
6 robins to 3 bluebirds
Number of bluebirds compared to number of robins:
3 bluebirds to 6 robins
Number of robins compared to total number of birds:
6 robins to 9 birds

3. Cassie could have also compared the birds using fractions
Cassie could have also compared the birds using fractions. (Remember there were 6 robins and 3 bluebirds)
What fraction of the total number of birds were robins?
What fraction of the total number of birds were bluebirds?

4. A ratio is a comparison of 2 quantities with the same unit.
What is ratio?
A ratio is a comparison of 2 quantities with the same unit.

5. Rabbits… Mark has 4 brown rabbits and 5 white rabbits.
We can use ratio to compare the numbers of brown and white rabbits.
For example – the ratio of brown rabbits to white rabbits is 4 brown rabbits to 5 white rabbits.
The ratio is 4 to 5 and is also written as 4 : 5

6. More practice… The ratio of white to brown rabbits is…
5 to 4, or 5 : 4
These are called part-to-part ratios
(because they are comparing two parts of a whole)
The numbers 4 and 5 are the terms of the ratio
Order is important in ratio. 5 : 4 is NOT the same as 4 : 5

7. Still more practice… You can also compare the parts to the whole.
Here are some other ratios you can use to compare the rabbits.
Brown rabbits to all the rabbits:
White rabbits to all the rabbits:
These are called part-to-whole ratios
(because they are comparing a part to the whole)
4 to 9 or 4 : 9 or
5 to 9 or 5 : 9 or

8. Part-to-whole ratios are often written as fractions.
4 to 9, or 4 : 9 is also
When we read a ratio that is written as a fraction, we say “four to nine”

9. Try these…
Write each ratio 2 ways
apples to pears
caps to shoes
roses to daisies
4 to 3 , 4 : 3
5 to 6 , 5 : 6
1 to 4 , 1 : 4

10. And these…
Write a ratio to show the numbers of:
ladybugs to ants
ants to ladybugs
ladybugs to insects
ants to insects
3 to 7 , 3 : 7
7 to 3 , 7 : 3
3 to 10, 3 : 10,
7 to 10, 7 : 10,

11. Assignment
Page 304/305 #