1. Variables and Graphing

2. Three types of Variables
What is a Variable?
Persons or objects that can be:
manipulated
controlled
measured
Three types of Variables
Independent
Dependent
Control

3. Independent Variable – I.V.
Something that is changed by the scientist
What is tested
What is manipulated
Ex: fertilizer use on plants

4. Dependent Variable – D.V.
something that might be affected by the change in the independent variable
What is observed
What is measured
The data collected during the investigation
Ex: How much the plants grew

5. Controlled Variable – C.V.
Variable that is not changed
Also called constants
Allow for a “fair test”
Also called “Standardized Variables”

6. ***not on note sheet – add in!***
Control Group – C.G.
***not on note sheet – add in!***
In some experiments it is necessary to have a CONTROL GROUP
This group DOES NOT receive the I.V.
It is used as a comparison

7. Example 1
Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.
Name the independent, dependent, and control variable

8. Independent: ages of kids
Answers:
Independent: ages of kids
Dependent: how long it took to complete puzzle
Control: type of puzzle

9. The temperature of water was measured at different depths of a pond
Example 2
The temperature of water was measured at different depths of a pond

10. Independent variable – depth of the water
AnSWERS:
Independent variable – depth of the water
Dependent variable – temperature
Controlled variable – thermometer

11. What things does a graph tell us?1.

12. 5 things every graph contains
1. Title – effect of IV on DV
2. Independent variable – x axis
3. Dependent variable – y axis
4. Scale – number increments
5. legend/key – short description about the graph