3.MD.4: Measure to the Quarter Inch and Make a Line Plot
Also written as 3.MD.B.4 and CCSS.MATH.CONTENT.3.MD.B.4 · Cluster: Represent and interpret data.
The Official Wording
Generate measurement data by measuring lengths using rulers marked with halves and fourths of an inch. Show the data by making a line plot, where the horizontal scale is marked off in appropriate units— whole numbers, halves, or quarters.
Common Core State Standards, Grade 3, Measurement & Data · Read it at the source · Checked October 14, 2026
What 3.MD.4 Means in Plain English
Third graders measure objects with a ruler marked in halves and quarters of an inch, then plot the data. Crayons from one bin might measure 3 1/4, 3 1/2 and 3 3/4 inches, so the line plot runs from 3 to 4 in quarter steps, one X per crayon.
This is 3.NF.2 put to work: the ruler is a number line cut into fourths, and so is the line plot. Second grade plotted whole units only (2.MD.9). In 4th grade the ruler adds eighths and students add and subtract the lengths on the plot (4.MD.4).
3.MD.4 I Can Statements
- I can measure a length to the nearest quarter inch.
- I can mark a line plot scale in halves or quarters.
- I can show each measurement as an X above its length.
3.MD.4 Worked Example
Eight crayons from one bin, measured to the quarter inch and plotted on a scale from 3 to 4 inches.
Eight crayons measure 3 1/4, 3 1/2, 3 1/2, 3 3/4, 3 1/2, 4, 3 1/4 and 3 1/2 inches. Show the data on a line plot.
- Find the shortest and the longest. The scale has to reach from one to the other.Shortest 3 1/4, longest 4: scale from 3 to 4
- The data comes in quarters, so cut the inch into 4 equal spaces and label every mark, like a ruler.3, 3 1/4, 3 1/2, 3 3/4, 4
- Tally the lengths first so no crayon gets lost or counted twice.3 1/4: 2, 3 1/2: 4, 3 3/4: 1, 4: 1
- Draw one X above the mark for each crayon, stacked evenly so taller stacks mean more crayons.2 Xs, 4 Xs, 1 X, 1 X
- Read it back: the tallest stack is the most common length.3 1/2 inches, 4 crayons
Check it: Count the Xs: 2 + 4 + 1 + 1 = 8, one for every crayon measured. The mark at 3 stays empty, and that is fine.
Common Mistakes with 3.MD.4
Lining up with the 1
A crayon started at the 1 on the ruler, so 3 1/2 inches is read as 4 1/2
Try this: Have students find the zero edge first and line up the crayon’s end with it, then read the mark at the other end.
A scale of only the measured values
The line labeled 3 1/4, 3 1/2, 4, spaced evenly, with 3 3/4 squeezed in or left out
Try this: Mark every quarter between the smallest and the largest value, even the ones with no Xs, so the line works like a ruler.
The half-inch mark read as a quarter
The longer middle mark between 3 and 4 read as 3 1/4 because it is the next mark after 3
Try this: Count the spaces in one inch first. Four spaces means quarters, and the middle mark is two quarters, the same as 1/2.
Where 3.MD.4 Fits
Practice 3.MD.4
Quick Check
- A pencil ends at the second mark after 5 on a ruler marked in quarter inches. How long is it?
- What labels go on a line plot from 2 to 3 marked in quarters?
- A line plot shows 3 Xs over 4 1/2, 5 Xs over 4 3/4 and 2 Xs over 5. How many objects were measured, and how many more were 4 3/4 inches than 5 inches?