Equivalent Fractions: Ordering Fractions by Making Common Denominators

GOAL: In this lesson you will learn how to order fractions.

GOAL: In this lesson you will learn how to order fractions. HOW: You will create common denominators and then compare numerators.

1 2 You know that fractions can be shown as part of a whole, part of a set, or on a number line as a value between zero and one. You know that the top number in a fraction is called a numerator and stands for the part of the whole. (draw 1) You also know that the number down below the line is the denominator and that represents all the parts that make up the whole. (draw 4) You know that the word equivalent means equal. When we talk about common denominators that means that the denominators of the fractions will be the same and you know that in order to find common denominators, you need to find the least common multiple between them.

The least common multiple is the smallest multiple that both the numbers share. Let’s take a look at how we use least common multiples when finding common denominators for fractions. Let’s take a look at the fractions 2/3, 1/2, 4/5. First we are only going to focus on the denominators – that’s the part of the fraction that we need to make sure is equal. So, what is the least common multiple that 3, 2, and 5 share?

Let’s skip count 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 Now, let’s skip count for 2,

4, 6, 8, 10, 12, 16, 18, 20, 22, 24, 26, 28, 30 Now, let’s skip count for 5 –

5, 10, 15, 20, 25, 30 Are any of these multiplies the same for all three denominators? Yes, the number 30 is the same for all three. So, in order to make equivalent fractions, we need to multiply. 2 x 20 / 3 x 10 = 20/30 1 x 15 / 2 x 15 = 15/30 4 x 6/ 5 x 6 = 24/30 Now we can put the numbers in order from least to greatest by comparing the numerators. 15, 20, 24

2 x 20 / 3 x 10 = 20/30 1 x 15 / 2 x 15 = 15/30 4 x 6/ 5 x 6 = 24/30 Now we can put the numbers in order from least to greatest by comparing the numerators. 15, 20, 24

In this lesson, you learned how to order fractions by creating common denominators.