Grade 6 → Number System → Fractions ↓
Comparing and Ordering Fractions
Understanding fractions
Fractions are parts of a whole. When we talk about fractions, we are referring to a way of expressing a number that is not a whole. A fraction is made up of two parts, the numerator and the denominator. The numerator is the top number, and the denominator is the bottom number.
1 - 2
In this example, 1
is the numerator and 2
is the denominator. The numerator tells us that we are talking about a portion of something that is divided into two equal parts.
Comparing fractions with the same denominators
When fractions have the same denominator, it's easy to compare them. You just compare the numerators because the parts are the same size. For example:
3 5 - vs - 7 7
The denominators are the same: 7
So, you can compare the numerators: 3
and 5
Obviously, 5
is greater than 3
, so 5/7
is greater than 3/7
.
Comparing fractions with different denominators
When fractions have different denominators, it's not as easy to compare them directly. We need to find a common denominator to accurately compare their sizes. Here's how you can do that:
Finding a common denominator
Let's look at an example:
2 3 - vs - 5 4
The LCM (least common multiple) of the denominators 5
and 4
is 20
We convert each fraction into an equivalent fraction with a denominator of 20
.
For 2/5
, multiply the numerator and denominator by 4
because 20 ÷ 5 = 4
:
2 × 4 8 ------ = --- 5 × 4 20
For 3/4
multiply the numerator and denominator by 5
because 20 ÷ 4 = 5
:
3 × 5 15 ------ = --- 4 × 5 20
now we have:
8 15 - vs -- 20 20
Comparing 8
and 15
, 15
is greater than 8
, so 3/4
is greater than 2/5
.
Visualization of comparison of fractions
Visual aids can be useful for better understanding fraction comparison. Consider plotting the fractions on a number line or using strips of equal length divided into parts to show relative sizes.
Fraction Bar: 1/4 |xxxx|----|----|----| 1/3 |xxxxxxx|xxxxxxx|---| Number Line: 0 1/3 1/2 2/3 1 -----o-----×-----×-----×-----o-----o---
Here, each different bar and number line representation makes the comparison clear.
Ordering fractions
Ordering fractions means arranging them in ascending or descending order. Just like comparing, this can be done for fractions with the same denominator or different denominators.
Sequences with the same denominators
Similar to comparing, when ordering fractions with the same denominators, you only need to compare the numerators. For example, here is a list of fractions:
3 1 4 - , - , - 8 8 8
To order them from smallest to largest:
1 3 4 - , - , - 8 8 8
In increasing order, fractions are arranged according to their fraction size.
Sequences with different denominators
Just like comparing, you need to find a common denominator to order fractions with different denominators. Consider the following fractions:
2 5 3 - , - , - 5 6 4
The LCM of 5
, 6
and 4
is 60
Convert each fraction using 60
as the common denominator:
2/5 = (2×12)/(5×12) = 24/60 5/6 = (5×10)/(6×10) = 50/60 3/4 = (3×15)/(4×15) = 45/60
now we have:
24 45 50 -- , -- , -- 60 60 60
These can be ordered from smallest to largest:
24 45 50 -- , -- , -- 60 60 60
This means that 2/5, 3/4, 5/6
is an ordered sequence.
Solve problems involving comparison and ordering of fractions
To understand how to implement comparison and ordering, consider practical examples:
For example, suppose you have three pieces of cake that represent 1/3
, 1/2
, and 1/6
of a cake. To find out who gets the most cake, you compare the fractions.
Find a common denominator for 3
, 2
and 6
, which is 6
Convert each fraction:
1/3 = 2/6 1/2 = 3/6 1/6 = 1/6
From smallest to largest, the fractions are 1/6
, 2/6
, 3/6
. So, 1/2
is the largest and represents the largest piece of cake.
Practice problems
Let's practice comparing and ordering fractions:
-
Compare fractions:
4/9
and7/8
.Solution: - Find LCM of 9 and 8: 72 - Convert 4/9 to 32/72 - Convert 7/8 to 63/72 - Therefore, 7/8 > 4/9
-
Order the fractions:
3/10
,2/5
,7/15
.Solution: - Find LCM of 10, 5, and 15: 30 - Convert 3/10 to 9/30 - Convert 2/5 to 12/30 - Convert 7/15 to 14/30 - In order: 3/10, 2/5, 7/15
Closing thoughts on fractions
Understanding how to compare and order fractions is an essential part of mathematical literacy. It allows you to make educated decisions based on numerical data and find patterns in different scenarios. Regular practice with fractions will increase your confidence and improve your arithmetic skills.