Adding Fractions
"Fractions"
This Flocab song introduces the concept of fractions and provides strategies for reducing them. Once students understand the numerator and denominator, they’ll be reducing with ease. This song is a great follow-up to a multiplication or division unit. It’s a fraction rap!
Greatest is highest,
Least is lowest,
We must be the greatest!
We’re adding fractions.
Fractions and decimals
Are just math’s special way of letting you know,
That you don’t have a whole number,
You’ve got a part,
"Forget that! Fractions are just too hard."
No they’re not.
A fraction has 2 parts,
There’s the numerator, that’s the number on top,
The denominator is down below,
And the dominator lets you know,
How many pieces of a thing there are in all,
So 2/9ths means there’s 9 in all,
The numerator is how many belong to you,
So 2/9ths means that you have 2.
To add fractions we need to make,
The dominators of the fractions the same,
So what do we do to
Make them the same?
The lowest common denominator.
Uh, cha-ching!
Find the lowest
Common denominator,
When you’re adding fractions. (x4)
You must find the lowest
Common denominator,
Yeah, but what’s that?
That’s the smallest number that
Both denominators go into,
So sharpen your pencils,
That’s the smallest number
Both denominators go into,
So sharpen your pencils.
Fractions look nice when they’re reduced,
So we reduce fractions like we’re cooking soups.
Now find a factor.
A factor is a number that will go into
Another number evenly,
So find a factor.
A factor is a number that will go into
Another number evenly,
So what are the factors of 8?
Y’all think about it, I’m gonna wait.
1,2,4,8. Those are the factors of 8.
Find the lowest
Common denominator,
When you’re adding fractions. (x4)
Here are a few other examples. If your fraction is 4/5, 4 is the numerator and 5 is the denominator. If your fraction is 15/17, 15 is the numerator and 17 is the denominator.
Now it's your turn. With the fraction 3/8, which number is the numerator and which is the denominator?
Now it's your turn. With the fraction 3/8, which number is the numerator and which is the denominator?
Here's an example. Let's say you want to add 1/5 + 2/3. You need to make the denominator the same to add them. What's the lowest common denominator for 3 and 5? It's 15. But you can't just change the denominator to 15 and leave the numerator the same. First, figure out what number you need to multiply the denominator by to make it 15. Then multiply the numerator by the same number. So here's what you'll do:
1/5 + 2/3 =
(3/3)x(1/5) + (5/5)x(2/3) =
3/15 + 10/15 =
13/15
Now you try adding 1/4 + 5/7
1/5 + 2/3 =
(3/3)x(1/5) + (5/5)x(2/3) =
3/15 + 10/15 =
13/15
Now you try adding 1/4 + 5/7
To reduce a fraction, divide the numerator and denominator by the same number. You can only reduce fractions when the numerator and denominator have common factors besides 1. (Learn more about factors below.) And you need to make sure that you'll get a whole number after you divide. Here's an example:
10/15 can be reduced to 2/3, because both the numerator and denominator are divisible by 5.
How can you reduce 3/6?
Why can't you reduce 2/7?
10/15 can be reduced to 2/3, because both the numerator and denominator are divisible by 5.
How can you reduce 3/6?
Why can't you reduce 2/7?
You know a number's factors with this simple test: If you divide the number by its factor, you'll get another whole number (with no remainder left over). So here are a few examples:
The factors of 10 are 1, 2, 5, 10.
The factors of 24 are 1, 2, 3, 4, 6, 8, 12, 24.
What are the factors of 15?
You'll always have an even number of factors for any number. Why do you think that is the case?
The factors of 10 are 1, 2, 5, 10.
The factors of 24 are 1, 2, 3, 4, 6, 8, 12, 24.
What are the factors of 15?
You'll always have an even number of factors for any number. Why do you think that is the case?
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