ALEX Lesson Plan


Adding and Subtracting Mixed Numbers

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  This lesson provided by:  
Author:Sherry Williams
System: Covington County
School: Fleeta School
  General Lesson Information  
Lesson Plan ID: 13223


Adding and Subtracting Mixed Numbers


During this technology based lesson, students learn how to add and subtract mixed numbers by exploring websites on the Internet. Students demonstrate their knowledge of fractions by participating in practice activities on the Internet.

 Associated Standards and Objectives 
Content Standard(s):
TC2 (3-5)
8. Collect information from a variety of digital sources.
Examples: online libraries, multimedia dictionaries
  • Using technology tools to organize information
  • Demonstrating efficient Internet search strategies
  • Example: keyword search
  • Evaluating electronic resources for reliability based on publication date, bias, accuracy, and source credibility
  • TC2 (3-5)
    9. Use technology tools to organize, interpret, and display data.
    Examples: spreadsheets, databases, electronic graphing tools
    MA2015 (4)
    14. Understand a fraction a/b with a > 1 as a sum of fractions 1/b. [4-NF3]
    a. Understand addition and subtraction of fractions as joining and separating parts referring to the same whole. [4-NF3a]
    b. Decompose a fraction into a sum of fractions with the same denominator in more than one way, recording each decomposition by an equation. Justify decompositions, e.g., by using a visual fraction model. [4-NF3b]
    Examples: 3/8 = 1/8 + 1/8 + 1/8; 3/8 = 1/8 + 2/8; 2 1/8 = 1 + 1 + 1/8 = 8/8 + 8/8 + 1/8.
    c. Add and subtract mixed numbers with like denominators, e.g., by replacing each mixed number with an equivalent fraction, and/or by using properties of operations and the relationship between addition and subtraction. [4-NF3c]
    d. Solve word problems involving addition and subtraction of fractions referring to the same whole and having like denominators, e.g., by using visual fraction models and equations to represent the problem. [4-NF3d]
    MA2015 (5)
    11. Add and subtract fractions with unlike denominators (including mixed numbers) by replacing given fractions with equivalent fractions in such a way as to produce an equivalent sum or difference of fractions with like denominators. [5-NF1]
    Example: 2/3 + 5/4 = 8/12 + 15/12 = 23/12. (In general, a/b + c/d = (ad + bc)/bd.)
    MA2015 (5)
    12. Solve word problems involving addition and subtraction of fractions referring to the same whole, including cases of unlike denominators, e.g., by using visual fraction models or equations to represent the problem. Use benchmark fractions and number sense of fractions to estimate mentally, and assess the reasonableness of answers. [5-NF2]
    Example: Recognize an incorrect result 2/5 + 1/2 = 3/7 by observing that 3/7 < 1/2.
    MA2015 (5)
    16. Solve real-world problems involving multiplication of fractions and mixed numbers, e.g., by using visual fraction models or equations to represent the problem. [5-NF6]

    Local/National Standards:


    Primary Learning Objective(s):

    Students will add and subtract mixed numbers. Students will write fractions in simplest form.

    Additional Learning Objective(s):

     Preparation Information 

    Total Duration:

    61 to 90 Minutes

    Materials and Resources:


    Technology Resources Needed:

    Computers with Internet access, LCD projector


    Students must have a basic understanding of fractions and mixed numbers.

    1.)Begin the lesson by reviewing what students already know about fractions. Allow students to demonstrate what they know by coming to the board and showing fractions.

    2.)Then go to the websites below and allow students to view presentations about mixed numbers and fractions.
    The teacher can select any of the tutorials he/she feels is appropriate for students' knowledge level.
    (Math Practice)
    This site has several attached presentations about fractions.

    (Adding and Subtracting Fractions)
    This site demonstrates how to add and subtract mixed numbers.

    4.)After teaching students how to add and subtract mixed numbers,
    - Find the Least Common Denominator (LCD)
    - Find the equivalent fractions.
    - Add or subtract the fractions and add or subtract the whole numbers.
    - Write answer in lowest terms,
    let students visit the websites for practice.
    (Adding Mixed Numbers)
    This site has practice problems for students to work on adding mixed numbers.

    (Subtracting Mixed Numbers)
    This site allows students to practice subtracting mixed numbers.

    6.)After students have a good understanding of how to add and subtract mixed numbers, allow them to demonstrate their knowledge by working problems from the website below. Keep track of students' work for a grade.
    (Visual Fractions)
    This site helps students understand fractions.


    Assessment Strategies

    The teacher will assess students' work on the computer for accuracy. The websites will show the teacher the number of problems each student gets correct and incorrect.





    Each area below is a direct link to general teaching strategies/classroom accommodations for students with identified learning and/or behavior problems such as: reading or math performance below grade level; test or classroom assignments/quizzes at a failing level; failure to complete assignments independently; difficulty with short-term memory, abstract concepts, staying on task, or following directions; poor peer interaction or temper tantrums, and other learning or behavior problems.

    Presentation of Material Environment
    Time Demands Materials
    Attention Using Groups and Peers
    Assisting the Reluctant Starter Dealing with Inappropriate Behavior
    Be sure to check the student's IEP for specific accommodations.