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Comparing fractions with the same denominator

CCSS Math: 3.NF.A.3, 3.NF.A.3d

Video transcript

- [Voiceover] Let's compare 2/4 and 3/4. First let's think about what these fractions mean. 2/4 means we have some whole, and we've split it into four equal size pieces, and we get two of those pieces. Maybe we can think about pizza for an example. We split a pizza into four equal size pieces, and we ate two of them. 3/4 means that same whole, that same pizza was again split into four equal size pieces, but this time, what's different is we got three of the pieces. So maybe from that description, we can start to think about which one is larger, but let's draw them also just to be sure that we can decide which one is larger. So for 2/4, we're gonna have a fraction, maybe it's a pizza, and it's gonna be divided, split into four equal size pieces. These may not be perfect lines, but should represent four equal size pieces. And we get two of those pieces. So this represents 2/4, two out of four. 3/4, again, will be the same as the four equal size pieces, but this time, we get three of the four. So, one, two, three of the four pieces. And this will represent 3/4. Now we can look at it visually and see very clearly that 3/4 is greater, or takes up more space, or we can say that 2/4 is less than 3/4. Remember this is the less than symbol 'cause we always want this open, bigger side facing our larger number. In this case, it's facing the second number. So we'll say 2/4 is less than 3/4. Each of these fourths is the same size, so two of them is less than three of the fourths. Here we can try one more, but this time, let's don't draw the picture. Lets' just think about what they mean and see if we can figure it out. So for 5/8, we have a whole, and it's been divided into eight equal pieces. For 3/8, same thing, eight equal pieces. But here in 5/8, we get five of those pieces, and in 3/8, we get three of the pieces. So the pieces are the same size. They're eighths on both side. These are eighths, and these are eighths, but here we have five of the eights, and here we have three. So if the pieces are the same size, five pieces is greater than three pieces or 5/8 is greater than 3/8. And here our open end, our bigger side is still facing our bigger number, but our bigger number is first this time, so this is the greater than symbol. 5/8 is greater than 3/8.