Adding and Subtracting Mixed Numbers

by Glenda A. Ellis 

This lesson was created as a part of the SMART website and is hosted by the Illinois Institute of Technology

Grade Levels: 7th  &  8th                                                       

Subject (s): Mathematics/Arithmetic

Introduction:  This lesson is designed to teach students how to add and subtract mixed numbers, as to nurture number sense and create a foundation and enthusiasm for mathematics. Many students are having difficulty understanding "how to" solve addition and subtraction of mixed numbers. This can be a  fun and interactive way for students to learn , and to helps students to create a feeling of accomplishment.

Purpose:   To assess students'  knowledge of adding and subtracting mixed numbers. Students will understand some ways in which to compute mathematics problems.

Objectives: Students will be able to:                

 Identify the difference between adding and subtracting  numbers (click on the picture) 


 Add and subtract mixed numbers (click on the plus or minus sign)

 Solve everyday math problems (click on the house)

                                                        now, stroll down to PLAY THE GAMES

  Mentally figure out the answers to problems  without the use of paper, pencils or calculators.        

Materials:   Chalkboard, paper, computer, pencils and overhead projector etc.
chalkboard  paper         Example of an Area Graph          Pencilsoverhead

Activities and Procedures:

    1.  Start the lesson with this statement: 

        Why it is important to measure recipe ingredients carefully? Compare this to adding and subtracting  mixed numbers.        

    2.  Review adding, subtracting, multiplying, and dividing numbers.

    3.  Play a game using a overhead projector to illustrate part of the answer and have students to complete the other part.

    4.  Explain how measurement of fractions are use in everyday life, such as cooking, clothes design and home improvement.

            A.    To double a recipe for baking cookies or baking a cake. Are Students able to bake a tasty cake?

            B.    Buying material for designing clothes.

            C.    Purchasing  tiles to cover a floor. Can students successful measure the correct amount of tile?

    5.  Emphasize to students that they should add or subtract the fractional part of mixed numbers before adding or subtracting the whole-number

         parts. This habit will help them recognize when they need to rename a mixed number because they cannot subtract the numerators.

    6.  Explain how to add two mixed numbers with different denominators.

    7.  Daily Quiz: Add or Subtract. Write the answer in simplest form.

         A. 1 2/3 + 1 1/6 =              B. 2 7/10 - 1 1/2 =                  C. 3 2/3 + 2 5/8 =                 D. 7 3/8 - 4 5/6 =

        (click on the word below)



     After completing the internet activities students will improve their math skills.

                                                   Rubric For Internet Math Activities

Technology base Performance Assessment. Students will explore several web sites. Students will master 90% of the internet activities.

Students will solve 80% of the internet activities.

Students will solve 70% of the internet activities.



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© Glenda A Ellis