2.MD.B.6

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.

 

Summary:

This standard is about students understanding that number lines are constructed with equal spacing, and therefore have a connection to measurement tools. This standard also speaks more to using/drawing a number line and understanding equal spacing between those numbers in order to use it to add and subtract whole numbers within 100.

Understanding the Standard:

    • The number line is an important tool that helps students see the relationship between measurement and numbers on that continuum. Practice with this tool in a variety of contexts will expand their knowledge of this relationship. For example, show students that moving to the right on a number line means they are adding, and moving to the left means they are subtracting.
    • Have students practice drawing number lines to utilize when solving addition and subtraction problems. Sometimes these number lines will have "jumps" in them when adding or subtracting large numbers (meaning students don't have to write every single whole number on a number line in order to use it to subtract a large amount).
    • Number lines and length measuring tools are very similar, but used for different purposes. They both have numbers in a continuum; however, measuring tools are created with an expressed "space" between numbers, whereas with number lines there is no set/definitive unit of measure between each number.

      Questions to Focus Instruction:

        • Can students represent numbers on a number line with equally spaced points?
        • Are students able to utilize the number line to calculate sums and differences fluently and represent that result on a number line?
        • Are students able to articulate how they can add and subtract on a number line?

          Skills

          Prior to: Students are able to identify numbers on a number line and recognize patterns found on that number line. Additionally, they should be able to identify numbers found prior to and after any given number and interpret addition and subtraction of lengths.

          At Grade Level:
          Students can create a number line and express numbers on it with equally spaced units much like that found on a ruler.

          Moving Beyond:
          Students will build upon previous knowledge to represent a variety of numbers on an equally spaced number line including fractional numbers.