Transcript Comparing and Ordering Fractions

Thursday
POD
 There are twenty kittens on a farm. Four are
orange, five are black, eight are white, and
three are gray.
 What fraction of the kittens are white?
 What fraction of the kittens are orange?
 Write two equivalents for each fraction.
Comparing and Ordering
Fractions
SPI 0506.2.9 Compare whole numbers,
decimals and fractions using the symbols
<, >, and =.
Objective
 We are going to compare whole
numbers and fractions using the
symbols <, >, and =.
Use your prior knowledge
 What have you learned about fractions so
far?
 You already know how to find equivalent
fractions.
 Today you will use what you know to compare
fractions.
Why do we need to know how to
compare fractions?
 Can you think of a reason?
 - TCAP Test : )
Think for a minute…Can you think of any jobs or
activities that would require you to compare
fractions??? Write them down.
Cooking
- Measuring
Working with tools
- Cabinets, building a fireplace
Working with ribbon
- knowing which ribbon is the widest
Working with ribbon
 Measurements are often recorded in halves,
quarters, and eighths of an inch.
 Why would it be important to compare
fractions with different denominators when
working with inch measurements?
 - If you are comparing two measurements,
such as ¼in. and 3/8in., you need to be able
to compare the fractions to tell which is
longer.
*COMPARING FRACTIONS WITH
THE SAME DENOMINATORS*
It is easy to compare fractions if
they have the same
denominator. All you have to do
is to compare their numerators.
If two fractions have the same denominator, the
larger fraction is the fraction with larger numerator.
Example1:
 Which is larger, 2/4 or 3/4 ?
 2/4 has only 2 fourth parts
 3/4 has 3 fourth parts
 Since the denominators are the same, 3/4 is
larger than 2/4, because 3 is larger than 2.
We write 2/4 < 3/4
Representation
2/4
2/4 < 3/4
3/4
Comparing numbers with common
denominators



When the denominators are the same, simply
compare the numerator.
<
2/7
6/7
Which is the greatest?
Order these fraction from least to greatest.
7/17; 16/17; 10/17
7/17, 10/17, 16/17
Try these
3
15
18
19
19
3
12
19
When there are whole numbers
Compare whole numbers first, then
fractions.
3 is much more than 18/19
.
What do you do when the
denominators are not the same?





You must find a common denominator.
To do this, write out the multiples of each
denominator.
The multiples are not the factors.
The multiples are the numbers you get when you
multiply the number.
For example 6/8 and 4/5
5: 5, 10, 15, 20, 25, 30, 35, 40, 45.....
Now let’s see
8: 8, 16, 24, 32, 40, 48, 56.....
For example 6/8 and 4/5
5: 5, 10,15, 20, 25, 30, 35, 40, 45.....
8: 8, 16, 24, 32, 40, 48, 56.....
Do you see a common multiple???
40
Use 40 as the common denominator.
6/8 x 5/5 = 30/40
4/5 x 8/8 = 32/40
.
Problem: Mr. White has ribbons with the following
widths: 7/12 in., ½ in., and 5/8in. He needs to use
the widest ribbon. Which ribbon is the widest?
 To find the answer we must know how to
compare fractions.
 Do our denominators match?
 Based on what you know (prior knowledge)
make an inference. What is the first thing we
should do?
 Find common denominators!
How do we find common
denominators???
 Common multiples
Our denominators are 12, 2, 8
2: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24
8: 8, 16, 24, 32, 40
12: 12. 24, 36, 48
Is there a common multiple?
Fraction pieces with partner
 Let’s Compare!
7/12
<
6/10
3/5
<
4/7
=
3/12
2/8
Using fraction pieces
 Come up with a question for a fellow
classmate.
 Write your problem down.
 Have the pieces they need to solve the
problem ready, but not put together.
Groups of 4
 Number yourselves 1-4
 #1 has halves, 3rds, and 11ths
 #2 has 4ths, 5ths, and 10ths
 #3 has 6ths, 7ths, and 12ths
 #4 has 8ths and 9ths
Tell whether the fractions are ordered from
least to greatest or greatest to least.
1) 2/3 ; 7/10 ; 8/9 ; 11/12
Least to greatest
2) 5/8 ; ½ ; 2/10
Greatest to least
3) 7/8 ; ½ ; ¼ ; 1/12
Greatest to least
Textbook page 230-231
 Do #s 7-12 in your spiral.
 When you are finished you may start on
homework.
 Homework: Worksheet that compares
whole numbers and fractions using
the symbols <, >, and =.
Before you leave!
 Ticket out the door! For extended writing
 If I was going to share my candy bar with you,
would you rather have 3/8 or 2/5?
 Write your answer on the “ticket out the
door” and explain why and how you made
that decision.
Don’t forget Homework
 Worksheet comparing and ordering fractions
using symbols.
 http://jamit.com.au/htmlFolder/app1005.html
 Shark and sock game
 http://jamit.com.au/htmlFolder/FRAC1005.htm
l#DiferentDen
 explanations