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Common Core Math2nd GradeMeasurement & Data

2.MD.9: Measure Objects and Make a Line Plot

Also written as 2.MD.D.9 and CCSS.MATH.CONTENT.2.MD.D.9 · Cluster: Represent and interpret data.

Make a Number LineAll 26 2nd Grade Math Standards

The Official Wording

Generate measurement data by measuring lengths of several objects to the nearest whole unit, or by making repeated measurements of the same object. Show the measurements by making a line plot, where the horizontal scale is marked off in whole-number units.

Common Core State Standards, Grade 2, Measurement & Data · Read it at the source · Checked October 14, 2026

What 2.MD.9 Means in Plain English

Second graders measure a set of real things, say eight pencils to the nearest centimeter, and show the results on a line plot: a number line from 12 to 15 with an X above each pencil’s length. Three Xs over 15 means three pencils were 15 centimeters.

The line plot is new in 2nd grade and joins two threads: measuring with a tool (2.MD.1) and the number line as a scale (2.MD.6). The data stays in whole units. In 3rd grade students measure to the half and quarter inch and plot those fractions (3.MD.4).

2.MD.9 I Can Statements

  • I can measure several objects to the nearest whole unit.
  • I can draw a line plot with every whole number on its scale.
  • I can put one X above the scale for each measurement.

2.MD.9 Worked Example

Eight pencils from the class bin, measured, listed and stacked as Xs on a scale that keeps every whole number.

Problem

Measure eight pencils to the nearest centimeter and show the lengths on a line plot.

A line plot of eight pencils
  1. Measure each pencil to the nearest whole centimeter and write the number down as I go.12, 15, 13, 15, 14, 15, 12, 14
  2. Draw a number line that runs from the shortest to the longest, with every whole number marked, even ones with no pencil.12, 13, 14, 15 along the bottom, evenly spaced
  3. Put one X above a number for each pencil that measured that length.12: XX 13: X 14: XX 15: XXX
  4. Count the Xs to make sure none of the eight pencils got lost.2 + 1 + 2 + 3 = 8
AnswerA line plot from 12 to 15 centimeters with 2, 1, 2 and 3 Xs. The most common length is 15 centimeters.

Check it: Eight pencils measured, eight Xs on the plot. Every number from 12 to 15 appears on the scale, including 13 with its single X.

Common Mistakes with 2.MD.9

Skipping a number nobody measured

A scale reading 12, 14, 15 because no pencil was 13 centimeters

Try this: Compare the scale with a ruler: every whole number gets a mark, and an empty number is information too.

One X per object, placed by name

Pencil names along the bottom and lengths written above them, which is a table, not a line plot

Try this: Ask what the numbers along the bottom are. On a line plot they are lengths, and each X is one object that had that length.

Rounding inconsistently

A pencil that is a bit over 14 recorded as 15, another just like it recorded as 14

Try this: Agree on the rule before measuring: read the nearest whole mark, and when it is exactly halfway, round up every time.

Where 2.MD.9 Fits

Comes Before1.MD.4Organize and interpret data with up to three categories.2.MD.1Measure with the right tool, which produces the data.
Alongside2.MD.6Use a number line with equally spaced whole numbers, which is the plot’s scale.2.MD.10Draw picture graphs and bar graphs of category data.
Comes Next3.MD.4Measure to the half and quarter inch and plot those on a line plot.4.MD.4Make a line plot of fractions and solve problems from it.

Practice 2.MD.9

Number Line GeneratorFree ToolA labeled line from 10 to 20, marked by ones, ready for the Xs. Every whole number is already on the scale, including the ones nobody measured.10 to 20Step 1Labeled
Make a Number Line
Graph Paper GeneratorFree ToolLarge squares keep the Xs in even stacks, so three Xs over 15 stand visibly taller than two over 14.Large squaresOne pagePrint
Make Graph Paper

Quick Check

  1. Eight pencils were measured. The line plot shows 2 Xs over 12, 1 over 13, 2 over 14 and 3 over 15. How many pencils were longer than 13 centimeters?
  2. No object measured 13 centimeters. Does 13 still go on the line plot’s scale?
  3. A line plot of shoe lengths has 4 Xs over 18, 3 over 19 and 1 over 20. How many shoes were measured?

2.MD.9: Other Names

2.MD.92.MD.D.9CCSS.MATH.CONTENT.2.MD.D.9

Common Core State Standards © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved. Official wording from the Common Core State Standards PDFs at corestandards.org, last checked October 14, 2026. The explanation, I can statements, example, mistakes and practice on this page are EMStudio’s own, written beside the official wording. They are not part of the standard.