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  3. 2nd Grade

Represent Whole Numbers on a Number Line

Using a number line to represent whole numbers as lengths is a second grade, Common Core math skill: 2.MD.6. Below we show a video that demonstrates this standard. Then, we provide a breakdown of the specific steps in the video to help you teach your class.

Prior Learnings

Your students will have learned how to measure objects through non-standard units, like using paperclips to measure a pencil (1.MD.1). They should also be able to compare objects using terms like longer, shorter, longest, and shortest (1.MD.2). 

Future Learnings

In the future, understanding how to measure objects with a ruler will help your students expand on and apply the concept elsewhere. Students will be able to make a line plot, measure objects, and place those measurements on the plot (2.MD.9). Your students will also be able to use rulers marked with halves and fourths of an inch (3.MD.3) and apply “linear measurement to measure perimeter and area” (3.MD.5- 8).

Common Core Standard: 2.MD.6 - Represent whole numbers as lengths from 0 on a number line

Students who understand this principle can:

  1. Create a number line, with equally spaced marks, to show whole numbers.
  2. Represent addition and subtraction problems on a number line.
  3. Solve addition and subtraction problems using a number line. 

A Video to Help You Teach Common Core Standard: 2.MD.6

Below we provide and breakdown the video to help you teach your students this standard.

Video 1: Using a Number Line to Solve Problems

The video starts by explaining that the number line is like a ruler, helping us to see numbers in the order in which we count them, starting from 0. Each number represents its distance from 0.

  1. The number 1 is 1 unit away from 0.
  2. The number 2 is 2 units away from 0.
  3. The number 5 is 5 units away from 0.
  4. So on and so forth.

Number lines can also help us solve addition and subtraction problems.

  1. 7 + 3 = ___
  2. Find 7 on the number line.
  3. The plus sign (+) means to add more, so count forward 3 units.
  4. The answer is 10.

Next, the video uses a larger number line:

  1. Solve: 40 - 13 = ___
  2. Find the number 40.
  3. The minus sign (-) means to subtract or take away, so count backward 13 units.
  4. The answer is 27.

‍Want more practice?

Give your students additional standards-aligned practice with Boddle Learning. Boddle includes questions related to Comparing and Measuring Lengths plus rewarding coins and games for your students to keep them engaged. Click here to sign up for Boddle Learning and create your first assignment today.

*Information on standards is gathered from The New Mexico Public Education Department's New Mexico Instructional Scope for Mathematics and the Common Core website.

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