Standard

Represent whole numbers as lengths from 0 on a number line diagram with equally spaced points corresponding to the numbers 0, 1, 2, ..., and represent whole-number sums and differences within 100 on a number line diagram.

Student language:

• "I can make and use a number line."

Explanation

About the Math, Learning Targets, and Rigor

This standard calls for the student to create number lines within100 to solve addition and subtraction problems. Students should create the number line with evenly spaced points corresponding to the numbers.

To solve problem using a number line:

1. Have students represent their addition and subtraction within 100 on a number line. They can use notebook or grid paper to make their own number lines.
2. Have them mark and label a line on paper with whole-number units that are equally spaced and relevant to the addition or subtraction problem.
3. Then have them show the addition or subtraction using curved lines segments above the number line and between the numbers marked on the number line.
4. Have them write the amount added or subtracted above each curved line or "jump."

Note: Drawing the curves or making the “hops” between the numbers will help students focus on a space as the length of a unit and the sum or difference as a length.

Example: 49 + 5

1. Start at 49 on the line.
2. Draw a curve to 50.
3. Continue drawing curves to 54.
4. Write the amount added above each curve or "jump."

Common Misconceptions

• Students may think that they always have to start at zero. Work with students to use the numbers in the problem to choose an appropriate starting location on the number line.
• Students may think they can only make jumps of 1. Students can make jumps of 5, 10, 20, etc. Challenge them to represent the same problem in two different ways on a number line and justify their reasoning.

Resources

Videos

• Khan Academy
  • scroll to find 2.MD.6, click on a skill, watch videos on left side in each skill
• Learn Zillion

EngageNY Lessons

Extra Practice

• North Carolina Tasks
• Illustrative Math Tasks
• Howard County Tasks
  • Click on 2nd grade at bottom, then 2.MD.6
• Common Core Sheets

Released Assessment Questions

2.MD.6-1 Student Example

2.MD.6-2 Student Example

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