How to graph Scatter Plots? (+FREE Worksheet!)

Use scatter plots to examine relationships between two sets of numerical data.

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A scatter plot is a graph that shows the relationship between two sets of data by plotting ordered pairs on a coordinate plane. Each point represents one observation with an x-value and a y-value. Scatter plots are a powerful tool in Algebra 1 for spotting trends, identifying correlations, and drawing a line of best fit. This lesson walks you through how to create and interpret scatter plots, with clear examples and practice problems.

Tutor-style math help

graph Scatter Plots: what to notice and how to work it

Statistics skill

Statistics is about describing data honestly. A calculation is useful only when it helps explain center, spread, shape, or association.

What to notice first

Ask what the display is trying to show. Histograms show shape, box plots show spread by quartiles, and scatter plots show association.

Common student mistake

Do not report a number without context. A mean, median, IQR, or regression line should answer a question about the data.

Key formulas and cues

$\text{mean}=\frac{\text{sum}}{\text{number of values}}$

$IQR=Q_3-Q_1$

$z=\frac{x-\mu}{\sigma}$

$\text{slope of best-fit line}=\frac{\text{change in prediction}}{\text{change in }x}$

A reliable path

Identify the questionDecide whether you need center, spread, shape, or association.
Use the right displayChoose a histogram, box plot, scatter plot, or summary statistic.
Write the meaningExplain what the statistic says about the data set.

Worked examples

Find IQR

Example: $Q_1=8$, median $=12$, $Q_3=20$

IQR measures the middle 50%.
Subtract Q1 from Q3.
20 – 8 = 12.

Answer: $IQR=12$

Read association

Example: A scatter plot rises from left to right.

As x increases, y tends to increase.
That is a positive association.
A best-fit line should have positive slope.

Answer: Positive association

Open pop-up practice

Try one before moving on

Try: Find the mean of 6, 8, and 10.

Answer: $8$.

Next step: do the matching worksheet or quiz while the method is still fresh, then come back and explain the first step in your own words.

What Is a Scatter Plot?

A scatter plot (also called a scatterplot or scatter diagram) displays two-variable data as a collection of points on a coordinate grid. The independent variable (the one you control or measure first) goes on the x-axis; the dependent variable (the one that responds) goes on the y-axis. Once you plot all the points, you look at the overall pattern to decide if the two variables are related.

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How to Graph a Scatter Plot

Step 1: Set Up the Axes

Choose a scale for both axes so all data points fit comfortably. Label each axis with the variable name and units.

Step 2: Plot Each Ordered Pair

For each row of data, locate the x-value on the horizontal axis and the corresponding y-value on the vertical axis, then place a point (dot) at that position. Example: the pair (3, 7) means $\color{blue}{x = 3}$, $\color{blue}{y = 7}$.

Step 3: Identify the Correlation

Look at the overall direction of the points:

Positive correlation: Points trend upward from left to right (as x increases, y increases).
Negative correlation: Points trend downward from left to right (as x increases, y decreases).
No correlation: Points are scattered with no clear direction.

Correlation can also be described as strong (points close to a line) or weak (points spread out).

Step 4: Draw a Line of Best Fit (Trend Line)

A line of best fit is a straight line drawn through the scatter of points so that roughly equal numbers of points lie above and below the line. It summarizes the trend and can be used to make predictions.

Step-by-Step Summary

Label the x-axis (independent variable) and y-axis (dependent variable); choose an appropriate scale.
Plot each data pair as a point (x, y) on the coordinate grid.
Look at the pattern: positive correlation, negative correlation, or no correlation.
Draw a line of best fit (trend line) that balances points above and below it.
Use the line of best fit to make predictions within or near the data range.

Watch: Constructing a Scatter Plot (Video Lesson)

Khan Academy demonstrates how to construct a scatter plot from a data table:

Scatter Plots – Worked Examples

Example 1: The table shows hours studied (x) and test scores (y) for 5 students: (1, 55), (2, 65), (3, 70), (4, 80), (5, 90). Describe the correlation.

As hours studied increase, test scores increase. The points trend upward from left to right. This is a strong positive correlation.

Example 2: A scatter plot shows outdoor temperature (x) and cups of hot chocolate sold (y). As temperature increases, sales decrease. What type of correlation is this?

As x increases, y decreases. This is a negative correlation.

Example 3: Data: (2, 8), (4, 5), (6, 9), (8, 3), (10, 7). Describe the correlation.

The points show no consistent upward or downward trend — they are scattered randomly. This data set shows no correlation.

Example 4: A line of best fit for a scatter plot of (hours of TV watched, GPA) passes through the points (1, 3.8) and (5, 2.2). If a student watches 3 hours of TV per day, predict their GPA using the line.

$\color{blue}{\text{ Slope } = (2.2 – 3.8)}$ ÷ $\color{blue}{(5 – 1) = (-1.6)}$ ÷ 4 = −0.4
Using point (1, 3.8): y = −$\color{blue}{0.4x + b}$ → 3.8 = −$\color{blue}{0.4(1) + b}$ → $\color{blue}{b = 4.2}$
At $\color{blue}{x = 3}$: y = −$\color{blue}{0.4(3) + 4.2}$ = −$\color{blue}{1.2 + 4.2}$ = 3.0

More Practice: Scatter Plots Explained (Video Lesson)

Simplifying Math provides an additional walkthrough of scatter plots, correlation, and lines of best fit:

Exercises: Scatter Plots

The points (1, 2), (2, 5), (3, 4), (4, 8), (5, 7) are plotted. Is the correlation positive, negative, or none? Explain.
A scatter plot of shoe size vs. height shows points trending upward. Describe the type and direction of correlation.
A scatter plot of car age (years) vs. resale value ($) shows points trending downward. What type of correlation is this?
Plot the points (0, 1), (1, 3), (2, 5), (3, 7), (4, 9) on a coordinate grid and draw a line of best fit. What is the equation of the line?
A line of best fit passes through (2, 10) and (6, 2). Predict the y-value when $\color{blue}{x = 4}$.
Explain why a scatter plot with all points forming a perfect diagonal line is considered a perfect correlation.

Answers

Positive correlation: as x increases, y generally increases.
Strong positive correlation: larger shoe sizes tend to go with taller heights.
Negative correlation: as car age increases, resale value decreases.
The points form a perfect line. $\color{blue}{\text{ Slope } = (9-1)}$÷$\color{blue}{(4-0) = 2}$; equation is $\color{blue}{y = 2x + 1}$.
$\color{blue}{\text{ Slope } = (2-10)}$÷($\color{blue}{6-2}$) = −8÷4 = −2; equation: y = −$\color{blue}{2x + 14}$; at $\color{blue}{x=4}$: y = −$\color{blue}{2(4)+14}$ = 6
Every point lies exactly on the line of best fit, so the relationship is perfectly linear — there is zero deviation from the trend.

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Frequently Asked Questions

How do you graph a scatter plot?

Draw an x-axis and a y-axis, label each with one variable and choose a scale that fits your data. Then plot each data pair as a single point, such as (3, 75) for 3 hours studied and a score of 75. Don’t connect the dots; instead, look at the overall pattern to see whether the association is positive, negative or none.

How do you graph a scatter plot on a TI-84?

Press STAT, choose Edit, and enter x-values in L1 and y-values in L2. Next press 2nd then Y= to open STAT PLOT, select Plot1, turn it On, and choose the first type, the scatter plot, with Xlist L1 and Ylist L2. Finally press ZOOM and choose 9:ZoomStat to fit the window to your data.

How do you graph a scatter plot in Excel?

Put the x-values in one column and the matching y-values in the next column. Select both columns, go to the Insert tab, and choose Scatter from the Charts group. Add axis titles from the chart elements menu so the graph is easy to read, and you can add a trendline to show a line of best fit.

How do you graph a scatter plot in Desmos?

Click the plus sign in Desmos and choose Table, then type your x-values in the first column and y-values in the second. Each row appears as a point on the graph right away. To check a line of best fit, type y1 ~ mx1 + b in a new line, and Desmos calculates the slope and intercept for you.

Is there an online scatter plot maker?

Yes. Free online graphing tools such as Desmos and spreadsheet programs like Google Sheets can make a scatter plot from a table of values in seconds. They are handy for checking your hand-drawn graph. Still, practice plotting points by hand on graph paper, since many classroom quizzes ask you to draw the scatter plot yourself.

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How to graph Scatter Plots? (+FREE Worksheet!)