Adding and Subtracting Like Fractions
Grade 3rd Grade · Math · 30 min
What's Included
Learning Objective
I can add and subtract fractions with like denominators.
Reading Passage
Adding and Subtracting Fractions
Imagine you have a yummy pizza cut into 8 equal slices. Each slice is one part of the whole pizza. We can write one slice as a fraction: 1/8. The bottom number, 8, tells us how many equal pieces there are in total. This is called the denominator. The top number, 1, tells us how many pieces we have. This is called the numerator.
What if you eat 2 slices? You ate 2/8 of the pizza. Then your friend eats 3 more slices. They ate 3/8 of the pizza. How much pizza did you both eat in total?
When fractions have the same bottom number, like 8, they have "like denominators." This means the pieces are the same size. To add fractions with like denominators, you just add the top numbers. Keep the bottom number the same. So, 2/8 + 3/8 = 5/8. You both ate 5/8 of the pizza.
Now, let's say there were 8/8 (a whole pizza) to start. If you both ate 5/8, how much is left? To subtract fractions with like denominators, you just subtract the top numbers. Keep the bottom number the same. So, 8/8 - 5/8 = 3/8. There are 3/8 of the pizza left. Remember, when the bottom numbers are the same, adding and subtracting fractions is easy!
Guided Notes
3 key concepts
- 1
In a fraction like 1/8, the bottom number is called the denominator and tells us the total number of equal pieces. The top number is called the numerator and tells us how many pieces we have.
- 2
When fractions have the same bottom number, they have like denominators. To add these fractions, you just add the top numbers and keep the bottom number the same.
- 3
To subtract fractions with like denominators, you subtract the top numbers and keep the bottom number the same.
Practice Questions
3 questions · Short answer
Exit Ticket
Quick comprehension check
“A cake is cut into 9 equal slices. You eat 4/9 of the cake. Your brother eats 2/9 of the cake. a) How much cake did you and your brother eat in total? b) How much cake is left from the whole cake (9/9) after you both ate your slices?”
Complete Lesson Package
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