Data and Line Plots
Grade 4 · Math · Study Guide
Learn how to collect, display, and analyze data using line plots and other data tools.
Data is information that is collected, organized, and used to answer questions. When you measure things like the length of pencils in a classroom or how many books students read each month, you are collecting data. After collecting data, you organize it to find patterns and answer questions.
A line plot is a diagram that shows data values on a number line with X marks (or dots) above each value. Each X represents one data point. Line plots make it easy to see how data is spread out, where most values are clustered, and what the highest and lowest values are.
Line plots in 4th grade often include fractions. For example, you might measure the length of different insects to the nearest 1/4 inch and then display those measurements on a line plot. To find the total of all measurements, you add all the values including the fractions. To find how many data points are above or below a certain value, count the Xs above or below that point on the number line.
Key statistics to know: The mode is the value that appears most often (the tallest stack of Xs). The range is the difference between the highest and lowest values. These help you describe and compare data sets.
Key terms
- Data
- Information that has been collected and can be used to answer questions or find patterns.
- Line plot
- A graph that shows data points on a number line, with Xs or dots placed above each value.
- Mode
- The value in a data set that occurs most often.
- Range
- The difference between the greatest and least values in a data set.
- Frequency
- How many times a particular value appears in a data set.
- Data point
- A single piece of information in a data set, shown as one X on a line plot.
Flashcards
- Line plot
- A number line with X marks above values to show how often each value appears in a data set
- Mode
- The value with the most Xs above it on a line plot; the most frequent value in the data
- Range
- Greatest value minus least value; shows how spread out the data is; e.g., data from 3 to 9 has range 6
- Reading a line plot
- Count each X to find frequency; the tallest stack is the mode; leftmost and rightmost values give the range
- Line plot with fractions
- Number line can show 0, 1/4, 1/2, 3/4, 1 ... each X above 1/2 means one item measured 1/2 unit
- Total from a line plot
- Multiply each value by its frequency and add all products; e.g., 3 items at 1/4 = 3/4, 2 items at 1/2 = 1
- Cluster
- A group of data points bunched together in one area of the line plot; shows where most values fall
- Gap
- An empty space on a line plot with no data points; shows values that don't appear in the data set
Questions
A line plot shows these values: 3, 3, 4, 4, 4, 5, 6. What is the mode?
- 3
- 4
- 5
- 6
Show answer
Answer: 4
The value 4 appears 3 times (more than any other value), so 4 is the mode.
If the lowest value in a data set is 2 and the highest is 9, the range is _____.
Show answer
Answer: 7
Range = greatest − least = 9 − 2 = 7.
On a line plot, each X mark above a number represents one data point.
Show answer
Answer: True
Each X on a line plot represents one individual measurement or data point from the set.
A line plot shows plant heights: 1/4, 1/4, 1/2, 3/4, 3/4, 3/4, 1. What is the total height of all plants combined?
- 3 inches
- 4 inches
- 4 1/4 inches
- 5 inches
Show answer
Answer: 4 1/4 inches
Total: (1/4 + 1/4) + (1/2) + (3/4 + 3/4 + 3/4) + 1 = 2/4 + 2/4 + 9/4 + 4/4 = 17/4 = 4 1/4 inches.
A line plot can only display whole number data.
Show answer
Answer: False
Line plots can display fractional data. In 4th grade, you often use line plots to show measurements like 1/4, 1/2, and 3/4 of a unit.
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