Lesson 5: Simple Fractions
Lesson 5: Simple Fractions
What a fraction is, and comparing fractions with the same denominator.
A fraction is a part of a whole. It has a numerator and a denominator. The numerator above the fraction line (bar) is used to count the parts out of the total. The number below the fraction line (bar) is called the denominator. It is used to name the total number of parts (fifth, tenth, thousandth, etc).
The denominator can never be 0, because we cannot divide by 0.
We can compare fractions, order them and perform various operations.
Fractions are frequently used in everyday life and many more complex mathematical concepts are based on this concept. For example, splitting or measuring something.
What You Will Learn in This Lesson
In this Grade 5 lesson you will learn about simple fractions and their properties.
You will learn and practice how to add and subtract fractions with the same denominators, as well as how to compare them. For example, you will discover that when the denominators are the same, the largest fraction is the one with the most parts (only comparing the numerators).
The lesson teaches how to identify equivalent fractions and how to reduce them to lowest terms. For example, 2 pieces our of 8 is the same as 1 piece out of 4. Thus, if we record these relationships as fractions they would be equivalent. Equivalent means “equal”. One can be reduced to become the other.
Fractions go hand in hand with decimals and percent and you will discover their relationships in the upcoming lessons.
Fractions Short Animation
Key ideas: Simple Fractions
A fraction shows part of a whole. In 3/8, the denominator (8) tells how many equal parts the whole is cut into, and the numerator (3) tells how many parts we have.
When fractions have the same denominator, compare the numerators: the bigger numerator is the bigger fraction. To add or subtract them, add or subtract the numerators and keep the denominator.
Worked examples
Example 1
A pizza is cut into 8 equal slices and you eat 3. What fraction did you eat?
- 3 of 8 equal slices: 3/8.
Example 2
Which is greater, 5/9 or 7/9?
- Same denominator, so compare numerators: 7 > 5.
- 7/9 is greater.
Example 3
Calculate a) 2/7 + 3/7 b) 5/6 − 1/6
- a) 2 + 3 = 5 sevenths: 5/7.
- b) 5 − 1 = 4 sixths: 4/6, which simplifies to 2/3.
Example 4
What is 3/4 of 20 stickers?
- Divide into 4 equal groups: 20 ÷ 4 = 5. Take 3 groups: 3 × 5 = 15 stickers.
Common mistakes
- Adding the denominators: 2/7 + 3/7 is 5/7, not 5/14.
- Using parts that are not equal in size.
- Thinking a bigger denominator means a bigger fraction (1/8 is smaller than 1/4).
Questions students ask
Why does the denominator stay the same when I add?
The size of the pieces does not change. You are only counting more pieces of the same size.
Grade 5 Simple Fractions Quiz
Check your understanding
Try the quiz for this lesson. You’ll see right away if each answer is correct.