What Is a Line Plot?

A line plot is a type of graph that uses a number line as its base and places an X mark (or dot) above the line for each data point. It shows how data is distributed - where values cluster, where they're sparse, and what the range is.

Line plots are introduced in grade 2 for whole number measurements, and by grades 4-5, students work with line plots that include fractions on the number line.

Parts of a Line Plot

Title - tells what data is being displayed
Number line - the horizontal base, labeled with relevant values
X marks - one X per data point, stacked above the corresponding value
Labels - units of measurement

Example: 7 students measured how many inches their bean plants grew. The data: 1, 2, 2, 3, 3, 3, 4 inches.

Line Plot: Bean Plant Growth (inches)

X
X  X  X
X  X  X  X
 -  -  -  -  -  -  -  -  -  -  -  -  - 
1  2  3  4

At a glance: most plants grew 3 inches; the range is 1 to 4 inches; no plants grew 0 or 5 inches.

How to Create a Line Plot

Collect your data
Find the smallest and largest values - these define your number line's range
Draw a number line and label it with equal intervals
For each data point, draw an X above the corresponding number
Add a title and label the unit of measurement

What Line Plots Show

Mode - the value with the most X marks (most common data point)

Range - the difference between the largest and smallest values

Clusters - groups of X marks bunched together (many values in that area)

Gaps - areas of the number line with few or no X marks

Outliers - data points far away from the rest

Line Plots with Fractions (Grades 4-5)

Upper grade students work with line plots that include fractional measurements on the number line. Common examples: lengths measured to the nearest 1/4 or 1/8 of an inch.

"Measure the length of each pencil to the nearest 1/4 inch. Make a line plot to display the data."

Practice Activities

Collect real classroom data (shoe sizes, number of siblings, hours of sleep) and create a line plot together as a class.
Give students a completed line plot and ask them to answer questions: "What is the mode? What is the range? How many students in all?"
Mystery line plot challenge: give students a line plot with no title and ask them to imagine what real-world data it could represent.
Create line plots with fractions using physical measurement data from a science activity.

Frequently Asked Questions

What is a line plot in math?

A line plot is a graph that uses a number line as its base and places an X (or dot) above the number line for each data point. If three students are 52 inches tall, there are three X marks above 52. Line plots are used to display measurement data and show the distribution - where data clusters, what the range is, and which values appear most or least often.

What is the difference between a line plot and a line graph?

A line plot uses a number line with X marks to show how many times each value occurs - it displays distribution. A line graph uses two axes (x and y) with dots connected by lines to show how data changes over time - it shows trends. They look similar in name but are used for different purposes. Line plots are introduced in grades 2-3; line graphs typically appear in grades 4-5.

How do you read a line plot?

To read a line plot: (1) Look at the number line - what values are shown? (2) Count the X marks above each value - each X = one data point; (3) Find the value with the most X marks - this is the mode (most frequent); (4) Find the range - the difference between the largest and smallest values; (5) Identify clusters (where X marks bunch together) and gaps (where there are few or no X marks).