ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
Math Videos 43 videos
Want to start your own business one day? Then this video is a must-watch. If you're just planning to keep working at Wendy's forever, then move along.
If you know your earnings, and you know how much you've spent, how do you calculate your profit? That's right - you hire an accountant. (Or, if you...
Math 5: Adding Fractions 119 Views
Share It!
Description:
If you've ever baked anything, chances are you've worked with a few fractions. For the sake of your loved ones, though, we hope you've never baked anything like this...
Transcript
- 00:14
Doug’s Grandma isn’t like the other Grandma’s on the block. [Doug's Grandma riding a motorcycle down the street]
- 00:17
For starters, she drives a motorcycle and raises alpacas…
- 00:19
Pretty strange…but the strangest thing to Doug?
- 00:22
Definitely Gram's taste in food. [Doug looking sad in his Grandma's kitchen]
- 00:23
Today she’s making something called Squid Bits…
Full Transcript
- 00:25
Which are kinda like what would happen if a squid married a granola bar and they had
- 00:29
babies. [Squid-topped granola bars on a plate]
- 00:30
Yep, life with Grandma is never dull.
- 00:33
Grandma only has one very small pan, so she needs to make sure ahead of time that the
- 00:36
amount of ingredients in the recipe will fit.
- 00:38
So she starts by adding up all the ingredients. [Grandma making a list of all the food ingredients]
- 00:41
She needs 3/4 of a cup of old-fashioned oatmeal and 1/4 of a cup of wheat germ.
- 00:45
These are easy to add because 3/4 and 1/4 have the same denominator…AKA the number
- 00:50
at the bottom of the fraction is the same…in this case 4.
- 00:53
When fractions have common dominators, all we have to do is add the numerators…AKA [Adding numerators and denominators on a notepad]
- 00:57
the numbers on the top of the fraction...in this case 3 and 1.
- 01:00
So Grandma adds 3/4 to 1/4 to get 4/4.
- 01:04
Doug is impressed that his Grandma knows how to do this…
- 01:07
Though he’s less impressed by the fact that she lets her alpaca in the kitchen while she [Alpaca stood in the kitchen with Grandma and Doug]
- 01:10
cooks.
- 01:11
The health inspector would probably give her a grade D.
- 01:13
It’s not long before Grandma runs into trouble.
- 01:16
Her recipe calls for 2/3 of a cup of freshly chopped squid.
- 01:19
And she has no idea how to add 2/3 to the 4/4 she’s already got.
- 01:24
She has unlike denominators now.
- 01:25
What’s a kooky Grandma to do? [Grandma looking confused at the fraction of chopped squid]
- 01:28
Doug feels bad and says he’ll help her…
- 01:30
As long as she promises to not make him eat the squid bits when they’re done. [Doug offering help to his Grandma as Alpaca walks by]
- 01:33
Grandma swears on the soul of her alpaca that Doug will be spared.
- 01:37
So Doug tells her "the main thing to remember is that we can’t add fractions unless they’re
- 01:40
denominators are the same."
- 01:41
To add fractions with unlike denominators, she has to find what’s called the least
- 01:45
common denominator.
- 01:46
Sometimes it helps to think of it as the least common multiple, too.
- 01:50
So with 3 and 4 the LCD is 12 because it’s the smallest common multiple of 3 and 4. [4 multiplied by 3 = 2 highlighted on a notepad]
- 01:54
Doug’s Grandma still isn’t quite getting it.
- 01:56
Okay…yeah…both denominators should be 12, but how are they supposed give both fractions
- 02:01
that kind of makeover? [A fraction receiving a makeover]
- 02:02
Doug tells her it’s no big deal.
- 02:04
They just have to multiply both the numerator and the denominator by the number that will
- 02:07
make the denominator 12.
- 02:09
So with 2/3 they multiply it by 4/4 to get 8/12… [Fractions multiplied together wrote in a notepad sheet]
- 02:13
And with 4/4 they multiply by 3/3 to get 12/12.
- 02:18
Grandma gets excited because she’s back in familiar territory. [Grandma looking excited in the kitchen]
- 02:20
Now that the fractions have a common denominator, all she has to do is add the numerators.
- 02:24
So that’s…8/12 + 12/12 = 20/12
- 02:28
Doug tells her 20/12 is kind of a wonky fraction.
- 02:32
Grandma is slightly offended, but Doug tells her to relax…it’s easy to de-wonkify. [Doug telling Grandma to relax as Alpaca walks behind them]
- 02:36
The best thing to do is reduce the fraction.
- 02:38
To do this, he asks himself…What’s the biggest number that will go into both 20 and
- 02:43
12?
- 02:44
Bingo…he thinks…4.
- 02:45
So he divides 20/12 by 4/4 to get 5/3. [20 divided by 12 calculation written on a notepad]
- 02:49
Now, Grandma has the hang of it, and no other fractions with unlike dominators give her
- 02:53
any trouble.
- 02:54
It’s not long before her squid bits come out of the oven piping hot. [Squid bits on an oven tray]
- 02:57
She scoops one up and tells Doug to open wide.
- 03:00
Doug complains that she swore on the soul of her alpaca…
- 03:02
Sure…she says…but I had my fingers crossed behind my back. [Grandma's fingers crossed behind her back]
- 03:06
Poor Doug.
Related Videos
Check out the best bias video ever made, courtesy of the most awesome and amazing educational website in existence.
No, this isn't a terrible new mint-peach bubble gum flavor...though it does tend to leave a bad taste in people's mouths.
Those settlers in Jamestown really should have settled down with all that land-stealing. Tobacco's bad for you anyway.
Being born out of multiple wars doesn't quite seem to fit the peaceful, polite Canadians we know and love today...oh wait, they were called The Bea...
Not every cartoon is meant to entertain small children while their mother gets some "Mommy time." There are also political cartoons, which are mean...