Lesson Plan : Addition and Subtraction of Unlike Fractions

Teacher Name:
 Ms. Vakil
 Grade 7-8

 Fractions Unit - Adding and Subtracting Fractions with unlike denominators.
 Students will be able to add and subtract fractions with unlike denominators by using their learned skills to find the greatest common factor and applying it to create fractions with like denominators.
 1. Students will be able to perform the addition and subtraction of like fractions. 2. Student will transition this skill to include unlike regular fractions that round easily.
 Overhead projector, transparencies, white boards, white board markers, pencils, notebooks, and calculators if necessary.
 DO NOW: Students will review greatest common factor by doing a problem to find the greatest common factor between two denominators. Good afternoon class, today we are going to learn to apply what we learned in the last couple of days about greatest common factor to our goal for today which is to add and subtract fractions with unlike denominators. Remember, when adding and subtracting fractions you must always always have the same denominator!
 I will demonstrate the steps to adding or subtracting fractions with unlike denominators: Here is our problem: 1/3 + 2/9. First can we add these fractions the way they are... no, because the denominators are not the same. Therefore, our first step is to find the GCF, which we learned about. After going through the process, I found that the GCF is 9. Now I must take that GCF and apply it to my fractions. What that means is that we want each of the denominators to be 9 so that the fractions will have like denominators and we can add the fractions. When multiplying fractions one must do to the top what he does to the bottom. With our first fraction 1/3 we had to multiply 3 by 3 to get to our 9. Therefore, we must multiply the top and bottom by 3 to get 3/9. For, the second fraction we need to multiply the fraction 2/9 by 1 to get a denominator of 9. Therefore, our second fractions result is 2/9. We need to add the fractions, 3/9 + 2/9 which we cand do now because the denominators are the same, the answer is 5/9. Repeat process for subtracting fractions.
 Students will practice the process demonstrated with me by doing a couple more problems.
 Students who need help find the GCF will use a calculator to assist multiplication.
Checking For Understanding:
 Students will complete an exit ticket of one subtraction and one addition problem.
 I will review the problems on the exit ticket after collecting the paper.
Teacher Reflections:
 I will assess the exit ticket to come to an understanding of whether or not the majority of my class understands adding and subtracting fractions with unlike denominators.

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