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Grade 2 · lesson 4 of 4

Model Addition and Subtraction as Number-Line Jumps

Mark the supplied start, move in the stated direction by the stated amount, and record the end.

About 15 minutes, plus any extended practice

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Supplied materials

  • Paper and a pencil; drawing and spoken explanations are welcome. An adult may read directions and options aloud.
  • Supplied worked-case record: Start at 28 and subtract 13.
  • All quantities and shape descriptions are supplied in the worked example and questions; no purchase or personal information is needed.

Learn the idea

A number line measures position from zero using equal intervals. Addition moves right and subtraction moves left. Jumps can be split into tens and ones while preserving the total distance. The start label is a position, not a jump itself.

Mark the supplied start, move in the stated direction by the stated amount, and record the end. Split a long move into tens and ones if useful. Check the move by taking the inverse jump back to the start.

Use equal intervals on the line. Subtraction moves left on a usual increasing number line. Draw arrows labeled with their direction and number of intervals.

  1. Draw arrows labeled with their direction and number of intervals.
  2. Follow the worked example. Point to each number or shape feature and say what it tells you.
  3. Mark the supplied start, move in the stated direction by the stated amount, and record the end.
  4. Try the question and then the three practice questions. Check your answers and explain any change you make.
Worked example

See the method in action

Start at 28 and subtract 13. Move ten left to 18, then three left to 15. The endpoint is 15. A rightward jump of thirteen returns to 28, checking both distance and direction. Moving right initially would model addition instead. Use equal intervals on the line. Subtraction moves left on a usual increasing number line. Draw arrows labeled with their direction and number of intervals.

Your turn

Check your reasoning

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Helpful tips
  • Use equal intervals on the line.
  • Subtraction moves left on a usual increasing number line.
Start at 35 on a number line and move left 14. What is the endpoint?

Feedback appears here after you check. This is practice, not a graded school assessment.

See the answer and explanation

21

A leftward fourteen-unit jump subtracts fourteen. The result is 21.

Take it further

Start at 46 and move right 27. Expected endpoint: 73.

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More practice: try new cases

Choose an answer for each problem. Explain your method on paper, then use the feedback to decide what to revisit.

More practice: try new cases
1. Start at 37 on a number line and move left 14. What is the endpoint?
Need a hint?
  • Use equal intervals on the line.
  • Subtraction moves left on a usual increasing number line.
2. Start at 39 on a number line and move left 14. What is the endpoint?
Need a hint?
  • Use equal intervals on the line.
  • Subtraction moves left on a usual increasing number line.
3. Start at 41 on a number line and move left 14. What is the endpoint?
Need a hint?
  • Use equal intervals on the line.
  • Subtraction moves left on a usual increasing number line.

Your choices are temporary. Feedback appears after you check all the answers.

Nothing here is saved to an account or sent to a teacher. Keep your own notes or download them before leaving. The score describes these questions; it does not certify subject mastery.

Check the subject sources

These LifeStarter passages, scenarios and exercises are authored for this Academy with AI assistance and review. External resources keep their publishers’ terms. A grade label suggests a starting level; it does not establish alignment with your school’s complete requirements.