Line Plots and Data

What Is a Line Plot?

A line plot (also called a dot plot) shows data on a number line. Each X or dot represents one data value.

Making a Line Plot

1. Draw a number line with the range of your data
2. For each data value, place an X above that number
3. Stack X's when values repeat
4. Add a title and label

Example

Heights of seedlings (in inches): $\frac{1}{4}, \frac{1}{2}, \frac{1}{4}, \frac{3}{4}, \frac{1}{2}, \frac{1}{2}, \frac{1}{4}, 1, \frac{3}{4}$

Plot these on a number line from 0 to 1, marking $\frac{1}{4}, \frac{1}{2}, \frac{3}{4}, 1$.

Reading Line Plots

From a line plot you can find:

• Most common value (mode): The value with the most X's
• Range: Highest value − Lowest value
• Total: Count all the X's
• Clusters: Where data groups together
• Gaps: Where there's no data

Solving Problems with Line Plots

Example: If the line plot shows seedling heights, you might answer:

• How many seedlings were measured? (Count all X's)
• What was the most common height? (Tallest stack)
• What is the total height of all seedlings? (Add all values)

Fractions on Line Plots

Line plots can show fractional values like $\frac{1}{8}, \frac{1}{4}, \frac{3}{8}, \frac{1}{2}$

To find the total of fractional data, add all the fractions: $\frac{1}{4} + \frac{1}{4} + \frac{1}{2} = \frac{1}{4} + \frac{1}{4} + \frac{2}{4} = \frac{4}{4} = 1$

Practice: Collect data about something in your class (shoe sizes, number of siblings) and make a line plot!