Line Graphs
Defining the Line Graph
A line graph is useful for displaying how data changes over time
or how quickly it increases or decreases.
Defining the parts of a line graph
Title: The title of the line graph tells us what the graph is about
Labels: The horizontal label across the bottom and the vertical label along the side tells us
what kinds of facts are listed.
Scales: The horizontal scale across the bottom and the vertical scale along the side tell us
how much or how many.
Points: The points or dots on the graph show us the facts.
Lines: The lines connecting the points show how much the data increases or decreases
between the points
Vertical (y-axis) label (with units)
1
8
6 Scale
Vertical
2
Data Points
4
Horizontal
5 Scale
9
3
Horizontal (x-axis)
label (with units)
3
Data Points
Vertical Scale
Dependent Variable
1 variable on dependent
2 variable
The effect of independent
Horizontal Scale
Independent
4 Variable
Procedure to Create a Line Graph
Step 1
Find the range in values (highest value - lowest value)
Step 2
Determine the scale (decide the value of each space)
Step 3
Label the graph (x- and y-axis labels)
Step 4
Plot the points and connect them
Step 5
Give the graph a descriptive title
You need DATA to create a line graph!
Ms. Meredith decided to analyze her sleep patterns over a week to see
where she could improve. On Sunday night, she received 5 hours of sleep.
On Monday, 7 hours. On Tuesday and Wednesday night, 8 hours. On
Thursday night she slept 4 hours. Friday night she slept 10 hours, and
Saturday night she slept 8 hours.
Create a data table to organize and display Ms. Meredith’s sleep patterns.
You need DATA to create a line graph!
Ms. Meredith’s Hours of Sleep in One Week
Day
Hours of Sleep
Sunday
5
Monday
7
Tuesday
8
Wednesday
8
Thursday
4
Friday
10
Saturday
8
Step 1:Find the range in values.
There are two sets of values.
● Which is the independent variable?
○ Day
● Which is the dependent variable?
○ Hours of sleep
○ What units are used?
■ Hours
● What are the highest and lowest values
for each variable?
○ IV: 10 to 4
○ DV: Friday to Thursday
Ms. Meredith’s Hours of
Sleep in One Week
Day
Hours of
Sleep
Sunday
5
Monday
7
Tuesday
8
Wednesday
8
Thursday
4
Friday
10
Saturday
8
Step 2: Determine a Scale.
Start with the horizontal scale. Test your numbers!
● You don’t want to squish everything in the graph. It should look
organized and the data properly spread out.
What’s wrong with
this graph?
Step 2: Determine a Scale.
● Start with the horizontal scale. Test your numbers!
○ If 1 square was equal to 1 day, would it look right?
○ How about 2? 3? Keep going - use most of the space, not all.
○ Place small lines where you want to place your data points.
Step 2: Determine a Scale.
10
9
8
7
6
5
4
3
Leave 2 2
spaces
1
for each
hour.
0
● Now try creating the vertical scale. Test your
numbers!
○ Remember, our data range was 4 to 10.
○ You should (almost) always start with 0.
○ If 1 square was equal to 1 hour, would all
of the data fit? Would it look right?
○ Could each square equal 1 hour? 2 hours?
3 hours? Keep going - use most of the
space, not all.
There are 21 spaces.
We should make the top of our graph greater than 10 so we don’t use
ALL the space.
If each space is 1 hour, it is too squished! Now what?!?
If every 2 spaces is 1 hour, then it’s more spread out!
Don’t make graphs that lie!
Your vertical
axis should
(almost) always
start with 0.
Hours of Sleep (hrs)
Step 3: Label the graph.
1
Day 2
Step 4: Plot the points and connect them.
Hours of Sleep (hrs)
Ms. Meredith’s Hours of
Sleep in One Week
Lines should
be clear, neat,
straight, and
all the same
thickness
Day
Day
Hours of
Sleep
Sunday
5
Monday
7
Tuesday
8
Wednesda
y
8
Thursday
4
Friday
10
Saturday
8
Step 5: Give the graph a title. What exactly does it show?
Hours of Sleep (hrs)
Ms. Meredith’s Hours of
Sleep in One Week
Day
Day
Hours of
Sleep
Sunday
5
Monday
7
Tuesday
8
Wednesda
y
8
Thursday
4
Friday
10
Saturday
8
Ms. Meredith’s Hours of Sleep in One Week
Hours of Sleep (hrs)
Ms. Meredith’s Hours of
Sleep in One Week
Day
Day
Hours of
Sleep
Sunday
5
Monday
7
Tuesday
8
Wednesda
y
8
Thursday
4
Friday
10
Saturday
8
Day of Week vs. Hours of Sleep
Hours of Sleep (hrs)
Ms. Meredith’s Hours of
Sleep in One Week
Day
Day
Hours of
Sleep
Sunday
5
Monday
7
Tuesday
8
Wednesda
y
8
Thursday
4
Friday
10
Saturday
8
Mass of Liquid vs. Volume Relationship
Find the relationship between the volume of water (mL) and Mass of water (g) by measuring the mass of
water using a 100mL graduated cylinder.
Good Morning 6-1!
Today’s tasks:
1. Create a bar graph using the data from the ping pong ball
experiment. The steps are the same, just spread out bars.
2. Complete the graphing worksheet (2 bar graphs, 2 line
graphs).
If you finish early:
1. Complete your individual practice assignments (write
your own procedures, create your own data table from a
question).
2. Become an organization master.
Step 1
Find the range in values
(highest value - lowest value)
Step 2
Determine the scale (decide the
value of each space)
Step 3
Label the graph (x- and y-axis
labels)
Step 4
Separate x-axis into even bars,
neatly spaced. Label each bar.
Step 5
Give the graph a descriptive title
Step 1
Find the range in values (highest value - lowest
value)
Step 2
Determine the scale (decide the value of each
space)
Step 3
Label the graph (x- and y-axis labels)
Step 4
Separate x-axis into even bars, neatly spaced.
Label each bar.
Step 5
Give the graph a descriptive title
https://www.mathgoodies.com/lessons/gra
phs/construct_bar
Scientific Method: Step 5
ANALYSIS
Interpreting Graphs
Defining the parts of a line graph
Title: The title of the line graph tells us what the graph is about
Labels: The horizontal label across the bottom and the vertical label along the side tells us
what kinds of facts are listed.
Scales: The horizontal scale across the bottom and the vertical scale along the side tell us
how much or how many.
Points: The points or dots on the graph show us the facts.
Lines: The lines connecting the points show how much the data increases or decreases
between the points
Vertical (y-axis) label (with units)
1
8
6 Scale
Vertical
2
Data Points
4
Horizontal
5 Scale
9
3
Horizontal (x-axis)
label (with units)
3
Data Points
Vertical Scale
Dependent Variable
1 variable on dependent
2 variable
The effect of independent
Horizontal Scale
Independent
4 Variable
Scientific Method: ANALYSIS
What are the steps so far?
1.
2.
3.
4.
5.
6.
7.
Observations
Research Question
Variables
Hypothesis
Materials and Methods
Data Collection: Tables and Graphs
Data Analysis: What does the data mean? What are the patterns? What is the evidence?
Scientific Method: ANALYSIS
A large part of the Data Analysis step is interpreting tables and graphs to find patterns.
1. Read the title, key, and labels
a. The title tells us the data displayed
b. The key explains symbols and colors used.
c. The labels tell us the variables in the graph.
Scientific Method: ANALYSIS
2. Draw conclusions based on the data
a. Analyze the differences in the graph’s
data and how the data changes
b. Decide how to best describe the graph
using words (see table below).
c. Be descriptive! Break the graph into
sections, then describe them in words:
i. “Between 1995 and 1997, the user
numbers increased slightly,
then…”
ii. “There is an extremely large
difference between column A and
column B.”
Let’s try it out...
1. Summarize what the graph is about.
a. How the number of internet users has
changed from 1995 to 2013.
2. What is the independent variable?
a. Year
3. What is the dependent variable?
a. Internet users
4. How many users were there in 2003?
a. 719
5. Outline how the data changes between:
a. 1995 and 1997
b. 2011 and 2013
6. Interpret the graph by summarizing what
the data tells us.