1. Examples: 12 out of 20, 12 boys and 8 girls
Ratios and Rates
What are some ways you can compare the number of boys to total students in this classroom?
Examples: 12 out of 20, 12 boys and 8 girls

2. A ratio is a mathematical way to compare two quantities
…you can compare part to part
In our example boys to girls
…you can compare part to whole
In our example boys to total
…you can compare whole to part
In our example total to girls

3. 12 to 20 A ratio can be written in 3 ways:
A ratio can be written in simplest form just like a fraction

5. A rate is a comparison of two quantities using different units
examples:
A unit rate is a rate where the denominator is one unit
examples:

6. How do you change a rate into a unit rate?
look at our previous example:
One method 
Divide the numerator by the denominator
Which is the same as
Dividing both the numerator and denominator by 4

7. Let’s practice on whiteboards

8. Try changing these to unit rates
Typing 300 words in 6 minutes
Running 15 km in 45 minutes
Solving 20 math problems in 30 minutes

9. Let’s see what happens to these “units” when solving a problem
Luke texts 25 words/minute. How many words can he text in 30 minutes?

10. Pete drives at a speed of 50 kilometers per hour
Pete drives at a speed of 50 kilometers per hour. How far will he go in 4 1/2 hours?
Katie counted 24 petals on one of the dozen roses that her boyfriend gave her. About how many petals would there be on all the roses together?

11. Using unit rates is a good way to compare…
Which is the better price?
$6.25 for 25 oranges or $7.20 for 30 oranges?

12. You can find unit rates in different ways…
In a table
From a graph
From an equation
M = 55G