Adding and Subtracting Fractions

Adding and Subtracting Fractions

By Erica ES]

How can I add and subtract fractions with unlike denominators?

Essential Question​

​

​I can use common denominators to add and subtract fractions.​

Learning Target

when I can find the common denominator and use it to add and subtract fractions. ​

I know I got it

​Math Lesson

Let's remember how to find common denominator

​https://www.savvasrealize.com/community/program/1b78f0e9-3a74-3f19-b8b1-24bfbe6c8c8b/28/tier/463486dc-08c0-3f68-a674-5fe49dade280/28/lesson/d35c0c25-81d9-328e-ae78-b7a8867fe91e/28/content/4b000b8d-50db-3a30-b82e-d38fced50376/31

Let's try it now!

Multiple Choice

What is the first step in solving this problem? $$\frac{1}{2}+\frac{1}{4}$$  

• You need to find a common denominator.

• You just add the numerator and denominators.

• You have to multiply the numbers.

Multiple Choice

Let's find the common denominator, what are the denominators in our problem? $$\frac{1}{2}+\frac{1}{4}=\frac{ }{ }$$  

• The denominators and 1, 1.

• The denominators are 2, 4.

• The denominators are 1, 4.

• The denominators are 1, 2.

Multiple Choice

What do I do now that I have found the denominators?

• I need to add them.

• I need to subtract them.

• I need to divide them.

• I need to find common multiples.

Multiple Choice

If my denominators are 2 and 4 what are the multiples of these numbers?

• 2: 2, 4, 6, 8

  4: 4, 8, 16

• 2: 1, 2, 3, 4

  4: 2, 3, 4, 5

• 2: 3, 6, 4

  4: 4, 7, 9

Multiple Choice

You found the multiples:

2: 2, 4, 8

4: 4, 8, 16

Which one do we use as our common denominator?

• 2

• 4

• 8

• 16

Multiple Select

Now what do I do after finding the common denominator?

• I have to make equivalent fractions for the fractions that do not have my common denominator.

• I have to change the fractions so that it is the same value but has the common denominator that I found.

Multiple Choice

$$The\ problem\ was:\frac{1}{2}+\frac{1}{4}\$$  

If my common denominator is 4 which fraction do I need to change?

• $$\frac{1}{2}$$  

• $$\frac{1}{4}$$  

Multiple Choice

What is the equivalent fraction for $$\frac{1}{2}$$  

• $$\frac{1}{2}$$  

• $$\frac{1}{4}$$  

• $$\frac{2}{4}$$  

Multiple Choice

What is our new equation after changing $$\frac{1}{2}$$  into it's equivalent fraction of $$\frac{2}{4}$$  ?

• $$\frac{2}{4}+\frac{1}{4}$$  

• $$\frac{1}{2}+\frac{1}{4}$$  

• $$\frac{1}{4}+\frac{1}{4}$$  

Multiple Choice

$$\frac{1}{2}+\frac{1}{4}=\frac{2}{4}+\frac{1}{4}=?$$  

• $$\frac{2}{4}$$  

• $$\frac{3}{4}$$  

• $$\frac{1}{2}$$  

• $$\frac{1}{4}$$  

Multiple Choice

What is the common denominator?

$$\frac{2}{5}+\frac{1}{3}$$  

• 12

• 13

• 14

• 15

Multiple Choice

Solve the problem.

$$\frac{2}{5}+\frac{1}{3}=$$  

• $$\frac{5}{6}$$  

• $$\frac{11}{15}$$  

• $$\frac{13}{15}$$  

• $$\frac{3}{8}$$