Author:
DAWNE COKER
Subject:
Mathematics
Material Type:
Activity/Lab, Assessment, Formative Assessment
Level:
Lower Primary
Tags:
  • Add
  • Addend
  • Addition
  • Cl8Assessment
  • Cluster 8
  • Equation
  • Expression
  • Missing
  • Number
  • Problem
  • Solve
  • Solving
  • Subtract
  • Subtraction
  • Task
  • Unit 8
  • Unknown
  • Word
    License:
    Creative Commons Attribution
    Language:
    English
    Media Formats:
    Downloadable docs

    Education Standards

    T4T Solving Unknown Addend Problems

    T4T Solving Unknown Addend Problems

    Overview

    This resource is from Tools4NCTeachers. 

    This file contains a set of 4 tasks (including scoring rubric and student recording sheet).  The tasks may be used for instruction or assessment.  Each focuses on solving a problem with an unknown addend.  

    Remix this resource to include student work samples or addtional tasks.

    Here is a sample task from this resource.  Click each attachment to access all fully-formatted tasks, rubrics, and materials.

    NC.1.OA.4

    Bob’s Missing Number

    Domain

    Operations and Algebraic Thinking

    Clusters

    Understand and apply the properties of operations.

    Add and subtract within 20.

    Standards

    NC.1.OA.4 Solve an unknown-addend problem, within 20, by using addition strategies and/or changing it to a subtraction problem.

    NC.1.OA.6  Add and subtract, within 20, using strategies such as:

    • Counting on
    • Making ten
    • Decomposing a number leading to a ten
    • Using the relationship between addition and subtraction
    • Using a number line
    • Creating equivalent but simpler or known sums

    Materials

    SF, pencil

    Task

    Read the problem aloud to the student.  Bob is trying to find the missing number in the following equation:  6 + ? = 13.  How would you help Bob find the missing number?  Show your work using pictures, numbers, or words.  Be sure you tell what number is needed to complete the equation.

     

    Continuum of Understanding

    Not Yet Proficient

    Response includes 0-1 of the descriptors in “Meets Expectations”

    Strategies Used:

    • Counting all
    • Counting on
    • Number line
    • Making a ten
    • Doubles, doubles +/- 1
    • Relating subtraction
    • Creating known sums
    • Other:

     

    Progressing

    Response includes 2 of the descriptors in “Meets Expectations”

     

    Meets Expectations

    Response includes all the descriptors in “Meets Expectations”

    • Identifies the correct number to complete the equation: 7
    • Uses a strategy for addition such as doubles, using known facts, making a ten, etc. OR changes the equation to subtraction to solve
    • Explanation is thorough and clear

     

    Standards for Mathematical Practice

    1.  Makes sense and perseveres in solving problems.

    2.  Reasons abstractly and quantitatively.

    3.  Constructs viable arguments and critiques the reasoning of others.

    4.  Models with mathematics.

    5.  Uses appropriate tools strategically.

    6.  Attends to precision.

    7.  Looks for and makes use of structure.

    8.  Looks for and expresses regularity in repeated reasoning.

     

     

    Bob is trying to find the missing number in the following equation:  6 + ? = 13.  How would you help Bob find the missing number?

     

     Show your work using pictures, numbers, or words. 

    Be sure you tell what number is needed to complete the equation.

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

     

    Scoring Examples

    This student received “Not Yet Proficient” because the student did not create a model or an equation to correctly represent the problem.  The student created two models in which the known numbers were added together to get a total of 19 and then incorrectly inserted the 19 into the equation 6 + 19 = 13.  This student could benefit from using concrete representations to help understand the meaning of the equal sign as well as strategies for solving a problem with a missing addend. 

     

    This student received “Progressing” because the student could solve the problem correctly using addition, but did not clearly explain the addition strategy.  There were 8 hops on the number line instead of 7 and the 13 was circled in the equation, which indicates a possible confusion about the unknown.  This student could benefit from additional opportunities to use and explain the number line strategy.  This might sound like, “I started at 6 and counted up 7 more until I got to 13.” 

     

    These students received “Meets Expectations” because they could correctly solve and clearly explain the thinking done to solve the problem.  Their strategies included using known facts and making a ten to solve.