Material Type:
Activity/Lab, Lesson, Lesson Plan
Lower Primary
  • Add
  • Addition
  • Cl6Lesson
  • Cluster 6
  • Inches
  • Length
  • Measure
  • Problem
  • Solving
  • Task
  • Unit 6
    Creative Commons Attribution
    Media Formats:
    Downloadable docs

    Education Standards

    T4T Arm Span

    T4T Arm Span


    This lesson is from Tools4NCTeachers.

    In this lesson, students use a measuring tape to measure, record, and compare the lengths of their arm spans.

    Remix this lesson to include pictures of students in action!  

    Here is a sample of this resource.  Click the attachment to download the entire fully-formatted lesson and support materials.

    Arm Span Problems


    In this lesson, students use a measuring tape to measure, record, and compare the lengths of their arm spans.


    Common Core Standard:

    Relate addition and subtraction to length.

    NC.2.MD.5 Use addition and subtraction, within 100, to solve word problems involving lengths that are given in the same units, using equations with a symbol for the unknown number to represent the problem.


    Additional/Supporting Standard(s):

    Measure and estimate lengths in standard units.

    NC.2.MD.1 Measure the length of an object in standard units by selecting and using appropriate tools such as rulers, yardsticks, meter sticks, and measuring tapes.


    Standards for Mathematical Practice:

    1.   Make sense of problems and persevere in solving them.

    2.   Reason abstractly and quantitatively.

    5.   Use appropriate tools strategically.

    6.   Attend to precision.


    Student Outcomes:

    • I can add and subtract lengths of the same unit within 100.
    • I can measure and solve problems involving these measurements by using drawings and equations with a symbol for the unknown length.



    • Measuring tapes or yardsticks
    • Math journal or blank paper for recording
    • Paper for creating a line plot
    • Blackline master attached


    Advance Preparation:

    • Students will need to have previous experiences using a measuring tape or yardstick
    • Students should be able to add within 100 so they will be able to approach these problems.
    • Teacher will need to copy the blackline master for each student or display the problems in some way.



    1. After students have had opportunities to use a measuring tape or yardstick and are comfortable using it, they will begin to use measurements to solve problems. This task involves measuring the arm span of each child in the classroom.
    2. Select a student to measure your wingspan. Model and explain the need for holding out your arms perpendicular to your body in a “T” shape and measuring from finger tip to finger tip to get an accurate measurement. If there is an odd number of students the teacher would then measure for the student as well. Model recording the measurement on the board and label the length with inches.
    3. Group pairs of students that work well together. Students will use the measuring tape to measure each other’s arm span and record the lengths in a math journal or on paper.
    4. Have students briefly share any challenges to measuring a friend as well as what they did to ensure accurate measurements (T shape, beginning at the zero line, measuring from finger tip to finger tip)
    5. Students will come back together to discuss the problems they will solve using their measurements. See the blackline master for four specific problems students are asked to solve. After the class briefly discusses the problems, the students find their partner and begin to work.
    6. Circulate around the room as students work on the problems. It is appropriate for some students to struggle with these problems and you can clarify the problems and guide their thinking using prompts and questions like those in the Questions to Pose section.
    7. While pair are working, have them add their individual measurements to a shared class chart.
    8. When most students have finished, discuss arm spans and how the problems were attacked. Discuss if the arm spans were similar in length or if there was a major difference.
    9. As a group, refer to the shared chart to compare some of the measurements. Be mindful of exceptionally tall or short students who may be uncomfortable with their measurements.
    10. Students use the shared measurements to write their own problems.
    11. Students trade problems in their pairs and solve each others. Then partners switch to other classmates to solve more problems.
    12. Discuss the problems and the patterns they noticed as well as how they solved the problems their classmates created.


    Questions to Pose:


    • Look at the tape measure. If we are measuring our arm span where will we start on the tape measure? Where will we start on the arm span?
    • After the teacher’s arm span is measured ask questions such as, “What do you predict the shortest arm span in our room will be? The longest student arm span? What do you think the difference between the shortest and longest armspan will be?”



    • How will you find the difference in your arm span and your partner’s arm span?
    • What will your equation look like?
    • Is there any other way to write the equation?
    • Would an empty number line help you solve any of the problems?
    • How can you see if your answer is correct?

    For writing their own problems:

    • What are you interested in knowing now that we have collected some data about our armspans?
    • How will you compare the measurements of your friends’ arm spans and your own?
    • What strategy(ies) might a friend use to solve the problem you have written?



    • Why did we use the measuring tape as our tool for measuring arm spans? Why might another tool be either more or less accurate when measuring someone’s body?
    • What did you learn from comparing your arm span to the arm span of someone else?
    • Why do you think this happened?
    • How do you think our measurements might be different if we tried this in a Kindergarten class? a fifth grade class? another second grade class?
    • What do you think would happen if you measured another adult’s arm span?
    • What patterns did you noticed when you solved your friend’s problems?
    • Are there certain types of problems that we use more often?
    • Were some of the problems more difficult than others? Why? Why not?


    Possible Misconceptions/Suggestions:

    Possible Misconceptions


    Students may not be able to solve the problems and write an equation showing how they solved each one.

    Allowing for partner or small group work may help students that are struggling.

    Students may not make their “X” marks the same size and will then not interpret the line plot accurately.

    Discuss making the “X” the same size as the ones on the line plot and observe as students add their mark so you can intervene and help if needed.



    Solutions: N/A





    Arm Span Task

    Name: ________________________________________________________



    1. What is the difference in your arm span and your partner’s arm span? Write an equation that shows how you solved this problem.








    1. Find another partner and compare your arm spans. Write an equation to show the difference in your arm span and your new partner’s arm span.








    1. Compare your arm span to the teacher’s arm span. Write an equation to show the difference in your arm span the teacher’s arm span.








    1. How many more inches would your arm span need to be to equal 100 inches? Write an equation to show how you solve the problem.