Subtracting Fractions with Equations

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The students will be able to subtract fractions using equations.

Big Idea

Factoring is the right answer!


15 minutes

In this lesson students will be using equations to solve problems requiring them to subtract fractions with unlike denominators. The lesson begins with a quick review of factors and then heads into the computer lab where students complete an interactive tutorial with Ms. Mathy on subtracting fractions with unlike denominators.  To end the lesson students will review their unit ‘I Can’ statements by demonstrating their mastery of the statements. 

To begin the lesson I have students take out their whiteboards so that we can review factors of common numbers.  I explain to the students that I will give them a number and they have to determine all the factors for that number.  The students need to record their answers on their white boards and at the end of a minute or so I ask students to share responses.  The numbers I choose to use for this opening activity are 24, 8, 17, 32, 40, 16. 


30 minutes

To introduce and practice the concept of subtracting fractions I have students work independently on an tutorial from Wisc Online(MP 5).  The tutorial takes them through a few examples of subtracting fractions then has them participate in answering five questions of their own.  I have students bring paper and a pencil with them to the lab to aid them in solving and making sense of the problems.  This interactive takes approximately 15 minutes if the students are reading all the required information associated with the tutorial. 

Upon returning to the classroom I have students discuss with their partner what they learned from the tutorial by sharing an example of their own(MP 4).


15 minutes

As we near the end of this unit students have explored almost all of the ‘I Can’ statements that are included in this unit.  I think a well-deserved reward on to them is that they highlight how much they have learned in the last 12 lessons by showing off their knowledge.

I display the ‘I Can’ statements that we have covered thus far and one we have left. 

I can explain the relationship between a part and whole.

I can create a model of a fraction.

I can create and identify equivalent fractions.

I can add and subtract fractions with like denominators.

I can add and subtract fractions with unlike denominators.

I can solve real world problems involving fractions. 

I can add and subtract mixed numbers.

Now it is time for the students to shine.  I tell them to pick any one of the ‘I Can’ statements that we have covered and model how they can do it by creating a written example.  Students may use any type of model they choose but the must have it written down in some way so that I can collect it. 

After about ten minutes I have students present their thinking to the class.  I collect the papers of all students and use this as a way to check for progress on the students understanding of fractions.