**Comparing Fractions Using LCM**

Try This Out!

Peter walked 3/4 of a mile and Brandon walked 1/4 of a mile. Which boy walked the farthest?

How do you know?

How would you write the answer using <, =, and >?

Moving On Up

Yesterday, we practiced finding the least common multiple of a set of numbers. Now we are going to take that knowledge and apply it to fractions! We'll be finding the Least Common Denominator (LCD).

Try This at Your Table

Alan spent 2/5 of the weekend playing video games. Christina spent 1/3 of the weekend playing video games. Who spent more time playing video games?

Step 1: Find the LCM of the

denominators (LCD)

!

3:

5: LCM:

Step 2: Make an equivalent fraction for 2/5 and 1/3 with the LCM as the denominator for both.

2/5 becomes...

1/3 becomes...

Step 3: Answer the question, use <, =, or >.

Who spent more time playing video games?

DOL

Compare these fractions using <, =, and >. SHOW ALL THE STEPS!

1. 4/5 and 3/4

2. 7/10 and 5/6

3. 9/12, 5/8, and 1/2

4. Miguel read 2/3 of the books in his library, and Jhakya read 7/9 of the books in her library. If their libraries are the same size, which person read more books? SHOW YOUR WORK!

How About This?

Amber ate 3/4 of a pie, and Amyah ate 2/3 of a pie. If both pies are the same size, which girl ate more pie?

Note: these fractions have

unlike

denominators, so it is more difficult to compare them. If both had a common, or

like

denominator, we could compare them as easily as we did with the walking example.

Let's Try It

To solve the 'pie' problem, we need to compare 3/4 and 2/3 using <, =, or >.

Step 1: Find the LCM of the

denominators

.

4: 4, 8, 12, 16, 20

3: 3, 6, 9, 12, 15, 18, 21

The LCM is:

12

Comparing 3/4 and 2/3

Step 2: Make an equivalent fraction for 3/4 and for 2/3 using your LCM as the new denominator for both (Least Common Denominator).

3/4 /12

2/3 /12

What did you get?

So which girl ate more?

How would you write that,

using <, =, or >?

Objective

I will be able to compare fractions

(<, =, or >) using the

Least Common Multiple (LCM).

Another Example!

Peanut Butter, try this one (Jelly coaches):

Compare 7/8 and 5/6

Jelly, try this one (Peanut Butter coaches):

Compare 3/4 and 5/7

If finished early

,

work on this problem:

Vincent watched 9/10 of a movie, and Jacky watched 12/15 of a movie. If the movies were the same length, who watched the most? Show your work!

Warm Up!

On your whiteboards:

Make an equivalent fraction:

3/4 /8

4/5 12/

Find the least common multiple:

3 and 8

5 and 6

Independent Practice

Compare these fractions using <, =, or >. DO BOTH SETS!

If

summer

is your favorite season, start with this set of problems:

4/5 and 11/15 8/9 and 4/6 9/12 and 3/4

If summer is

not

your favorite season, start with this set of problems:

6/7 and 12/14 5/6 and 3/4 1/2 and 5/9

EVERYONE try these examples!

1/2, 3/4, and 2/3 1/3, 1/4, and 2/5

http://www.online-stopwatch.com/full-screen-stopwatch/?ns=../s/1.mp3&nslen=1