Transcript What is a ratio? - pams

What is a ratio?
Think
Write
Share
A ratio is….
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A comparison of two numbers.
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It can be written several ways
As a fraction
 Using a colon
 Using the word to
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Let’s find the ratio of
girls to boys in the class
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Write it three ways on your dry board
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What is the ratio of teachers to
students in the class?
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Write it three ways on your dry board!
Remember to always
simplify- yes- even a ratio
can be simplified!!
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Express each ratio as a fraction in
simplest form:
 4 goals to 10 attempts
 2/5
Express each ratio as a
fraction in simplest form:
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15 dimes out of 24 coins
 15/24
 5/8
Express each ratio as a
fraction in simplest form:
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4 weeks to plan 2 events
 4/2
 2/1
What if…
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You are comparing units?
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What is a unit?
Think
 Write
 Share
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3 feet to 16 inches
 We must first convert our larger units
into smaller units.
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How could we change feet into inches?
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Think, Write, share
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Multiply 3 feet by 12, because there are
12 inches in 1 foot.
3 feet (12) = 36 inches
16 inches
16 inches
Don’t forget to simplify!
36/16 = 9/4
Try some on your dry
board:
11 gallons to 11 quarts
 Change gallons to quarts.
 How many quarts are in a gallon?
 1 gallon = 4 quarts
11gallons (4 ) =44 quarts
11 quarts
11 quarts
44/11 = 4/1
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Try:
18 miles to 18 yards
 How many yards are in a mile?
 1760 yards = 1 mile
18 miles(1760) = 31680 yards
18 yards
18 yards
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31680/18= 1760/1
Try:
10 inches to 3 feet
 12 inches = 1 foot
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10 inches = 10 inches
3 feet (12)
36 inches
10/36= 5/18
Ratios…..
Pass out WS 375
 Students will complete numbers 1-12
on own
 Pass out talking slips
 Students will pass out to group
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Talking slips
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The number on your talking slip is the
number of the problem you will be explaining
to your team.
You do not have to go in order
Who ever places their talking slip in the
center of the table is the ONLY PERSON
SHARING
Others may agree or disagree with your
answer.
When all questions have been answered
place your slips back in the baggy!
What is a rate?
Think
 Write
 Share
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A rate….
A ratio of two measurements
 They have different kinds of units
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Examples:
 Miles/gallon
 Dollars/pound
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Can you think of any
more examples of rate?
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Write them on your dry board.
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Share with your team
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Share with the class
What is a unit rate?
Think
 Write
 Share
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A unit rate is when a rate
is simplified so the
denominator is equal to
one.
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18 dollars/ 20 CDS
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How much is 1 CD?
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To find the unit rate divide both the
numerator and the denominator by the
denominator!
18 dollars ÷ 20 = 0.9
20 CDS ÷ 20 = 1
Each CD costs 0.90 cents each!
Try some on your dry
board:
Find the unit rate for each rate:
 $3 dollars for 6 cans of tuna.
 To find the unit rate I want to find out how
much one can costs.
 Divide the numerator and denominator by 6.
$3 ÷ 6 = 0.5 1 can of tuna is 0.50 cents
6÷6
1
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Try: Find the unit rate
140 miles on 6 gallons
140 miles ÷ 6 = 23.33 miles
6 gallons ÷6
1 gallons
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23.3 miles/gal
Try: Find the unit rate:
25 feet in 3.2 hours
25 feet ÷ 3.2 = 7.8125 feet
3.2 hours ÷ 3.2 1 hour
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7.8125feet/hr
You will get a WS
Put your name on the top
 You will solve a problem
 When you hear the buzzer, rotate
papers
 Simultaneous Roundtable
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