1. Bell Ringer List 5 things that all good graphs should have.
(Ex: Title)

2. Step 1: Label Axes X-Axis Y-Axis
Independent Variable: “Cause”
The variable that we have chosen to change.
Y-Axis
Dependent Variable: “Effect”
The variable that changes due to the independent variable
Example: A football player kicks a ball,
and it lands some distance away.
Cause – independent
Effect - dependent

3. Example (The distance “depends” on how hard the player kicks it).
Example: A football player kicks a ball, and it lands some distance away.
The Independent variable (X-Axis)
how hard the player kicks the ball
The Dependent variable (Y-Axis)
the distance the ball travels
(The distance “depends” on how hard the player kicks it).

4. Try It On Your Own Read Worksheet 1 “Making Line Graphs” Practice:
Identify the Independent Variable (Cause)
Identify the Dependent Variable (Effect)

5. Step 2: Title and Labels Labels
independent variable (units)
Dependent variable (units)
Dependent vs. Independent
Labels
Write the full name
include the UNITS!!!
The title of the graph is always going to be written as:
dependent variable
vs.
independent variable.

6. Step 3: Determine Scale Origin: Axis Scale
Will always be point (0, 0)
Axis Scale
Must go up by consistent amount (equal intervals)
Ex: Interval of 5’s (0, 5, 10, 15, …)
Note: The #’s on the x-axis and y-axis do NOT need to go up by the same interval.

7. Step 3: Determine Scale for the axis
Data range: the difference between the lowest and highest value of the data.
Example: lowest: 25 degrees C
highest: 110 degrees C
Range: __________ degrees C 85
Number of lines on the graph: 25
85 degrees ÷ 25 lines =
Adjusted scale: round-up and use 4 degrees/line
3.4 degrees/line
(calculated scale)

9. Step 4: Plotting Points Data table
Set of (x, y) coordinates
Ex: the first point on the graph is located at (5, 8)
Plot all of the points from the data table
DO NOT connect the points on the graph

10. Step 5: Best-Fit Line Used to show a general trend in the data
Draw a single, straight line through middle of data
Must be drawn with a “straight edge” such as a ruler
Note:
Line may or may not go through point (0, 0)
This is ok!!!
Line does not need to go through any of the points
Roughly same # of dots above and below line

11. Slope
Slope measures the change between two points
Rate of change

12. Rise/Run Method Find two “Easy” Points
From point 1 to point 2 find how much to:
Go up by (“Rise”)
Go over by (“Run”)
Slope = Rise/Run
5 4 3
2 1 0
Rise
RUN
Rise: 2, Run: 4. Slope 2/4 = .5

13. Formula Method 1. Find any 2 points on the line
5 4 3
2 1 0
Rise
RUN
1. Find any 2 points on the line
2. Pick one to be point 1, the other as point 2
3. Determine coordinates (x, y) for each
4. Plug these in to the formula
Point 1: (1,2) Point 2 (5, 4) – 2 = = .5
5 –

14. Example What is the slope of these graphs?
Rise/Run: 7-4/3-0 = 3/3 = slope of Rise/Run: 6-2/2-0 = 3/2 = slope of 1.5

15. Determine Slope of Lab Rat Graph
Slope = Rise/Run or
32-8 = = .8

16. y-intercept
y-axis number where the “best-fit” line crosses the vertical (up/down) axis
Gives the “initial conditions”
Determine y-intercept of Lab Rat data

17. Bell Ringer 1. Find the slope
2. CPS students decided to collect data on the Time Spent Studying and their Test Scores.
Independent variable?
Dependent variable?
Point 1 (0,2) Point 2 (2,6) Y2-y1 / x2-x1 = (6-2)/(2-0) = 4/2 = slope of 2 Independent: Time spent studying. Dependent: Test Scores

18. Answer Problem #1 Point 1 (0,2) Point 2 (2,6)
y2-y1 = (6-2) = 4 = slope is 2
x2-x (2-0)

19. Answer Problem #2 Independent Variable (x-axis)
Time spent studying
Dependent Variable (y-axis)
Test Score
(Time Spent Studying) causes a change in (Test Score) and it is not possible that (Test Score) could cause a change in (Time Spent Studying)
The test score depends upon the time spent studying