Fraction Addition and Subtraction

2/3 + 2/3 =

• They don't speak the same language. We must find the common multiples of 3 and 3.

• 4/6

• 4/3

• 4/9

When we add and subtract fractions, they must _____ the ____ __________.

• talk; French language

• speak; same language

• add; same denominator

• dance; same ballerina

What should Carl do next?

• Circle "6" and use it as the common denominator

• Circle "12" and use it as the common denominator

• Add 1/3 + 3/4 and get 4/7

• List all of the multiples of 1

Why are the denominators both 12 on the bottom?

• Because 1/3 x 3/4 = 3/12 - when we multiply 12 is the denominator

• Because you can pick any denominator you want - it's a free country, isn't it?

• Because 12 is the lowest common multiple of both 3 and 4

• Trick question! The denominator SHOULD be 24!

What goes in the pink box?

• x4

• x3

• x12

• x1

What goes in the RED box?

LOOK CLOSELY: what mistake has CJ made?

• Trick Question - CJ never make no mystak

• CJ skipped 10 - 10 is a multiple of both 3 and 9.

• CJ didn't circle 9 - 9 is the lowest common multiple!

• CJ didn't multiply 3 and 9 together and get 27!

Why are the denominators both 9 on the bottom?

• Because 9 is the least common multiple of both 3 and 9.

• Trick question! The denominator could and SHOULD be 18!

• Because we always choose the highest denominator to add or subtract.

• Trick question! The denominator SHOULD be 27!

TAKE YOUR TIME: finish solving the problem.

• 2/0

• 4/9

• 8/9

• 2/9

How do you feel about adding and subtracting fractions?

• I GOT THIS and I can teach someone else!

• I GOT THIS! Hit me with some more.

• I think I'm getting it, but I need more practice.

• I still need help!