Subtracting Fractions and Mixed Numbers with Unlike Denominators and with
Regrouping Lesson Plan
Subject(s): Mathematics
Objective(s): The mathematician will subtract fractions and mixed numbers with unlike denominators by
regrouping.
Purpose: Students need to subtract fractions and regroup them in math and science and in real world
applications such as recipes.
Prerequisite Skills: Students will know how to find the least common denominator to create equivalent
fractions. Students will know how to add fractions and mixed numbers with common denominators.
Students will know how to convert improper fractions into mixed numbers.
Grade Level: 6
Materials:
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Graphic Organizer Notes page
PowerPoint with model
Homework
Internet Websites
Anticipatory Set: Tell me what you know about subtracting fractions and mixed numbers. You find a
common denominator to make it easier. Then you just subtract the numerator in the fraction. You
subtract the whole numbers together too. Think back to changing improper fractions to mixed numbers.
How did we do that? You divide the numerator by the denominator to get a whole number. The
remainder becomes your new fraction’s numerator and you keep the same denominator. Guess what?
That’s exactly what you are doing today and you already know it! We are just putting it all together.
Input:
Use PowerPoint to review the following. Ask students what it means to borrow when subtracting
numbers. Show the example 834 – 159. Have students tell how they would subtract this. Go to the
website: http://nlvm.usu.edu/en/NAV/frames_asid_155_g_2_t_1.html. Ask students how they would
model the subtraction problem given. Borrow a ten and change it to 10 ones. Using the applet, model
what the students answer. Then connect borrowing to regrouping of fractions. Show examples in
PowerPoint. Move to the Graphic Organizer notes. Ask students how they would model
.
Have students copy model onto their notes. Go through the example showing both processes
(regrouping and changing to improper fractions). Model the regrouping process. When modeling the
improper fraction process, question students how they used the same process when adding fractions.
Have them recall what they did and show the similarities in the process (everything is the same, except
now the last step is to subtract instead of add). Then students will work the next example in their
groups. Review student’s answers by completing the graphic organizer.
Next, have students go to the website: http://www.wisconline.com/objects/index_tj.asp?objID=ABM701 and practice subtracting mixed numbers with
regrouping. Discuss what they did.
If time allows, work more examples on marker boards.
Modeling: Students will view the PowerPoint that models subtracting fractions with unlike
denominators. Teacher and students will model the examples on their graphic organizer.
Check for Understanding: Teacher will circulate the room while students work on group examples. If
marker board examples are used, teacher will check for understanding when students put their boards
up.
Guided Practice: Teacher will guide students through first two examples on graphic organizer.
Closure: Have students summarize one of the processes on their graphic organizer. Then pair up
students who did different processes. Students will read to each other the summaries they wrote.
Discuss: How did we subtract fractions today? Was this the same process we had used before? What
new step did we add today? How did you regroup when you subtract fractions?
Independent Practice: Homework
Enrichment: Holt Challenge page:
http://my.hrw.com/math06_07/teacher/osp/msm1_tx/data/chap05/section04/challenge.pdf
Remediation: One-on-one tutoring and Holt Reteach pages:
http://my.hrw.com/math06_07/teacher/osp/msm1_tx/data/chap05/section04/reteach.pdf
Standard(s):
6.1 B Number, operation, and quantitative reasoning. The student represents and uses rational numbers
in a variety of equivalent forms. The student is expected to: generate equivalent forms of rational
numbers including whole numbers, fractions, and decimals
6.2 Number, operation, and quantitative reasoning. The student adds, subtracts, multiplies, and divides
to solve problems and justify solutions. The student is expected to:
(A) model addition and subtraction situations involving fractions with objects, pictures, words, and
numbers;
(B) use addition and subtraction to solve problems involving fractions and decimals
6.11 A Underlying processes and mathematical tools. The student applies Grade 6 mathematics to solve
problems connected to everyday experiences, investigations in other disciplines, and activities in and
outside of school. The student is expected to: identify and apply mathematics to everyday experiences,
to activities in and outside of school, with other disciplines, and with other mathematical topics.