1. Fractions
March 10, 2011

2. Fractions Agenda Review Adding and Subtracting Mixed Numbers
Multiplying Fractions
Multiplying Mixed Numbers

3. Let’s Go!

4. Warm-Up
Let’s review adding and subtracting fractions. Using your notes and the key words list, you will complete Lesson Practice page 43.
For questions 3-7, underline the key words that tell you which mathematical operation to use.
You will have 15 minutes to complete. Your teachers will ask you for answers. She may even call you up to the board to solve the problem.

5. 4 things you need to know by the end!!
1. How to change whole numbers to fractions
2. How to change mixed numbers to fractions
3. How to cross-simplify fractions when multiplying
4. How to multiply fractions

6. 1. How to change whole numbers to fractions!
Looking at the two examples below. Write a rule for changing a whole number to a fraction. Provide two examples.
4 = 4 1
2 = 2
Write your rule and examples
in your notebook.
To change a whole number to a fraction, you need to …

7. 2. How to change mixed numbers to fractions!
Multiply the denominator x the whole number (because it is asking how many parts of the denominator you have). Add the result and the numerator and put it over the denominator. OR change the whole number to a fraction and add them.
x3= =

8. 3. How to cross-simplify when multiplying!
Sometimes, fractions use big numbers. This is fine, since we are AWESOME mathematicians. However, it’s easier to simplify before multiplying.
Check it out…. x
You can cross-simplify before multiplying. This is ok because you are going to combine the denominators and numerators.
Cross-simplifying means you look at the top of one number and the bottom of the other and divide by the GCF (greatest common factor)!
So… 4 and 8 are both divisible by….?
3 and 15 are both divisible by…..?

9. 3. How to cross-simplify when multiplying!
Sometimes, fractions use big numbers. This is fine, since we are AWESOME mathematicians. However, it’s easier to simplify before multiplying.
Check it out….
x x
You can cross-simplify before multiplying. This is ok because you are going to combine the denominators and numerators.
Cross-simplifying means you look at the top of one number and the bottom of the other and divide by the GCF (greatest common factor)!
So… 4 and 8 are both divisible by….?
3 and 15 are both divisible by…..?

10. 4. Multiplying fractions.
Multiplying fractions isn’t a problem.
Multiply the top, then the bottom! x
One times one is ….
Five times two is …..
So the answer is……

11. 4. Multiplying fractions.
Multiplying fractions isn’t a problem.
Multiply the top, then the bottom!
x =
That makes sense because I am taking half of 1/5. 1/10 is half the size of 1/5.
One of these is half of one of these!

12. You have 3 minutes to copy.
Multiplying Fractions
5 X 2
Step 1: Divide 5 and 15 by the Greatest Common Factor or GCF.
Factors of 5 are 1, 5 and the factors of 15 are 1, 3, 5, and 15. The GCF is 5. 1
5 X 2
Note: Not all fractions have a GCF. 3
Step 2: Divide 8 and 2 by the GCF which is 2.
Remember the factors of 8 are 1, 2,4, and 8. The factors of 2 are 1 and 2. So the GCF is 2. 1 1
5 X 2 4 3
Step 3: Multiply X 1 = 1

13. Let’s Go!

14. ✔For Understanding
Multiply these fractions (Cross-simplify first if you can!)
2 X 4 = 6
7 X 7 =
8 9

15. You Have 3 minutes to Copy
Multiplying a whole number and a fraction 5 X 2 3 Step 1: Rename the whole number to an improper fraction. 5 = 5 1 Step 2: Multiply the numerator and multiply the denominators. 5 X 2 = 5 X 2 = Step 3: Convert the improper fraction to a mixed number in simplest form. 10 = 3 1

16. Let’s Go!

17. ✔For Understanding
If Jo and Helena each ate 3/8 of a pizza, how much of the pizza did they eat altogether? Hint: Jo + Helena =

18. ✔For Understanding Answer

19. You Have 3 minutes to Copy
Multiplying Mixed Numbers Step 1 Convert each mixed number to an improper fraction. Step 2: Look for the GCFs. If there are none, then multiply. Step 3: Covert the improper fraction to a mixed number.
Remember Multiply the Whole Number and the Denominator. Then add the Numerator. 2X5 =10+3 = 13 5

20. Let’s Go!

21. ✔For Understanding
Complete Lesson Practice handout page 47. you will have 15 minutes.