Adding with the Same Denominator

​This is a review of adding fractions from

3rd grade to 6th grade

​

• The FIRST time you go through the lesson lets see what you know. READ and STUDY the slides to prepare for the questions.​

• ​The SECOND time you go through you want to increase your score.​

• The Goal? By THIRD attempt you are at 100%.​

Reviewing parts of a fraction

• Numerator = the top number

• Denominator = the bottom number

Multiple Select

What is the top number of a fraction called?

• Denominator

• Numerator

Multiple Select

What is the bottom number of a fraction called?

• Denominator

• Numerator

Adding fractions with a common denominator

• Add the numerators

• Keep the denominators the same

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Multiple Choice

$$\frac{1}{6}+\frac{3}{6}=$$  

• $$\frac{2}{6}$$  

• $$\frac{4}{6}$$  

• $$\frac{4}{12}$$  

Multiple Choice

$$\frac{4}{9}+\frac{4}{9}=$$  

• $$\frac{8}{9}$$  

• $$\frac{4}{9}$$  

• $$\frac{8}{18}$$  

Multiple Choice

Which of the following equations is true?

• $$\frac{4}{8}+\frac{2}{8}=\frac{6}{16}$$  

• $$\frac{5}{10}+\frac{2}{10}=\frac{7}{10}$$  

• $$\frac{2}{7}+\frac{2}{7}=\frac{5}{7}$$  

Multiple Choice

Which of the following is true?

• undefined 

• $$\frac{2}{6}+\frac{3}{6}=\frac{5}{12}$$  

• $$\frac{2}{5}+\frac{2}{5}=\frac{4}{10}$$  

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What if my DENOMINATORS are DIFFERENT?

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Then here are some strategies...​

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EASIEST COMMON DENOMINATOR

Multiple Choice

Is this a correct answer?

• Yes, the student correctly added.
• No, you cannot add unlike denominators
• No, 5 + 7 is not 12
• No, 2 + 3 is not 5

Multiple Choice

What is the first step in solving this problem? 
⅘ + ½ =

• Add the top parts of the fraction
• Rewrite the fractions in the simplest form. 
• Find a common denominator. 
• Make each fraction into an improper faction. 

Multiple Choice

What is the sum of these fractions?

• 4/5
• 3/20
• 17/20
• 4/20

Multiple Choice

• 1/12
• 1
• 2/35
• 23/25

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EASIEST COMMON DENOMINATOR

is sometimes called the BUTTERFLY METHOD

Adding fractions with different denominators

• Multiply the denominators (to get a common denominator - QCD)

• Multiply the numerator of the first fraction by the opposite denominator

• Multiply the numerator of the second fraction by the opposite denominator

​But wait!!! There's another way to add and subtract unlike fractions!

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LEAST COMMON DENOMINATOR

Multiple Choice

$$\frac{1}{3}\ +\frac{2}{6}\ =\$$  

• $$\frac{4}{6}$$  

• $$\frac{2}{3}$$  

• $$\frac{3}{6}$$  

Multiple Choice

$$\frac{2}{3}\ +\ \frac{2}{9}\ =$$  

• $$\frac{8}{9}$$  

• $$\frac{4}{9}$$  

• $$\frac{2}{3}$$  

Multiple Choice

1/2 + 2/3 + 1/6

• 4/11
• 1  2/3
• 1  1/3

Multiple Choice

2/3 + 1/6

• 3/9
• 1/6
• 5/6

Multiple Choice

1/8 + 11/16

What needs to be the common denominator?

• 13/16

• 6/8

• 12/16

• 1/8

Multiple Choice

What is the the next step to finding this answer?

• Add the numerators (1+1=2)
• Multiply 12 X 1 for both fractions to find a new numerator
  
• Multiply to find each new numerator by the multiple used to get 12. (3 X1) (4 X 1)
• This is a mistake, you don't need to convert to twelfths

​But wait!!! There's another way to add and subtract unlike fractions!

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We will call this method

EQUIVALENT FRACTIONS​

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​NOW HERE IS THE

7th Grade Version

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Make sure you understand the first part of the lesson before you move on​

Multiple Choice

What is a common denominator for 1/3 and 1/2?

• 2

• 3

• 5

• 6

Multiple Choice

In the problem on the front of the video screen (-6/10 + (-2/8)), would you add the fractions or subtract them? Would the answer be positive or negative?

• Add

  and

  Negative

• Add

  and

  Positive

• Subtract

  and

  Negative

• Subtract

  and

  Positive

Finding Common Denominator

You can multiply the numerator and the denominator by the same number.

Multiple Choice

Simplify the given addition problem.

Make sure you reduce your answer.

• $$\frac{7}{6}$$  

• - $$\frac{1}{3}$$  

• $$\frac{1}{3}$$  

• - $$\frac{7}{6}$$  

Multiple Choice

What is a common denominator for 1/2 and 2/6?

• 2

• 6

• 10

• 12

Multiple Choice

$$Evaluate\ -\frac{3}{8}\ +\ \left(-\frac{2}{12}\right).\$$ Make sure to simplify your answer.

• - $$\frac{1}{4}$$  

• - $$\frac{13}{24}$$  

• $$\frac{13}{24}$$  

• $$\frac{1}{4}$$  

Finding Common Denominators

You can multiply the numerator and denominator by the denominator of the other fraction.

Multiple Choice

Find $$\frac{1}{6}+\frac{-5}{9}.$$    Simplify and reduce your answer.

• - $$\frac{4}{15}$$  

• $$\frac{2}{5}$$  

• - $$\frac{7}{18}$$  

• $$\frac{7}{18}$$  

Multiple Choice

What is a common denominator for 1/3 and 3/5?

• 15

• 3

• 3

• 10

Multiple Choice

Simplify. Be sure to simplify your answer. $$-\frac{2}{7\ }-\frac{2}{3}.$$  

• - $$\frac{4}{10}$$  

• - $$\frac{2}{5}$$  

• - $$\frac{20}{21}$$  

• $$\frac{20}{21}$$  

Finding Common Denominators

You can list the multiples of each of the denominators, then find smallest number the appears in both lists.

Multiple Choice

What is a common denominator for 1/4 and 2/6?

• 4

• 12

• 6

• 16

Multiple Choice

What is the sum of these fractions? 3/4 + 1/5

• 19/20

• 4/4

• 4/5

• 4/20

Multiple Choice

What is the sum of these fractions? 1/4 + 2/3

• 3/4

• 3/3

• 11/12

• 3/12