1. For example, what is − ?

3.
You have already learned how to subtract mixed number fractions with common denominators
When the denominators are the same, when the models are the same size, we can clearly see to subtract the numerators.

4. 3 4 8
1 2 4
2 2 4
When subtracting mixed number fractions, students think they should subtract the whole numbers, numerators, and the denominators. As you can see, this won’t work! We do not have the same sizes in order to subtract from. We do not have a common denominator! How would we model the answer? We cannot!

5. 3 4 8
3 4 8
1 2 4
1 4 8
So, how do we subtract mixed number fractions that do not have a common denominator? Such as the fractions: 3 4/8 – 1 2/4
When we divide the area model to find the common denominator, we are also creating our equivalent fraction so we can subtract to solve!
in order to add or subtract something, the pieces must be the same size Can you think of a way to make the area models so that they are divided up into the same amount of pieces? Yes
in order to add or subtract something, the pieces must be the same size

6. 3 1 2
3 2 4
1 1 4
1 1 4
2 1 4
in order to add or subtract something, the pieces must be the same size
When we divide the area model to find the common denominator, we are also creating our equivalent fraction so we can subtract to solve!
in order to add or subtract something, the pieces must be the same size Can you think of a way to make the area models so that they are divided up into the same amount of pieces? Yes

8.
1 3 5
LearnZillion Notes:
Remember that we must use a common denominator

9. Create a subtraction mixed number fraction problem
Create a subtraction mixed number fraction problem. Solve the problem and model your answer using fraction bars.
Create a subtraction mixed number fraction problem. Solve the problem and model your answer using fraction bars and number lines.
Write out your reasoning for your solutions.

10. What is ?
What is ?