Dividing Fractions

"Keep, Change, Flip"



This video uses the 'Keep, Change, Flip' mnemonic to teach students how to divide fractions. Keep the first fraction the same, change the division sign to multiplication, flip the second fraction over, then solve it the same way as a multiplication problem, by multiplying the numerators and denominators. The song shows students this process with an example problem and explains the math behind it.



Keep, change, flip, yeah that’s the action,
Everybody’s gonna know how we’re dividing fractions.
Keep, change, flip, yeah that’s the action,
Everybody’s gonna know how we’re dividing fractions. (x2)


Dividing fractions is easy, that’s no lie,
You just flip one, yep, then you multiply.
Don’t flip both because that’d be strange,
You need to keep one exactly the same.
Yeah, then the sign gets changed,
Division to multiplication, that's okay.
Then flip the second fraction like you’re on a grill,
We multiply what’s left, that’s really real.

Take 35 ÷ 23,
Keep, change, flip, that’s the word.
Keep 35 the same,
Change the sign so we multiply, that’s the game.
Flip 23, we get 32,
Then we can multiply, and so should you.
3 × 3 = 9, 2 × 5 = 10,
910, can’t reduce it, that’s the end.

Why do we flip it? I’ll explain the math,
Dividing by 2 is the same as multiplying by half,
20 students in your class ÷ 2
Would be 10 students, or we could do
20 × 12 = 10,
You'll see you'll get the same thing to the end.
Dividing is multiplying by the reciprocal,
Keep, Change, Flip, yeah, that’s the simple rule.

Keep, change, flip, yeah that’s the action,
Everybody’s gonna know how we’re dividing fractions.
Keep, change, flip, yeah that’s the action,
Everybody’s gonna know how we’re dividing fractions. (x2)


‪Keep, change, flip! Dividing fractions is no problem when you have this mnemonic to guide you through the process.


Using ‘Keep, change, flip' is simple. Keep the first fraction as is, change the sign from division to multiplication, and flip the second fraction, putting the numerator on the bottom and the denominator on the top. Then multiply the two fractions to solve.


‪Solve 3 5 ÷ 2 3 using ‘Keep, change, flip.'
Step 1: Change the division sign to multiplication.
3 5 × 2 3
Step 2: Flip the second fraction.
3 5 × 3 2
Step 3: Multiply.
3 5 × 3 2 = (3 × 3) / (5 × 2) = 9 10

‪Dividing by 2 and multiplying by 1 2 are actually the same thing.

10 ÷ 2 = 5

10 1 × 1 2 = 10 2 = 5

‪The reciprocal of a fraction is its ‘flipped' counterpart--the denominator of one is the numerator of the other, and vice versa. The reciprocal of 2 3 is 3 2 , and the reciprocal of 5 6 is 6 5 .
Dividing by a fraction and multiplying by that fraction's reciprocal will always give you the same thing.
When we divide fractions, do we need to make the denominators the same first?
Nope. You don't need to make the denominators the same to multiply or divide fractions.
In ‘keep, change, flip,' what does keep mean?
Keep one fraction the same
What do you change?
Change the division sign to multiplication
What do you flip?
Flip the second fraction, switching the numerator and denominator
Dividing is multiplying by the _______
Reciprocal
What's the reciprocal of 4 7
7 4
What's the reciprocal of 1 3
3 1 = 3

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