1. Warmup 8/23/2016
Write down all the factors you can think of that affect how much a plant grows

2. Scientific Method - Variables

3. What affects plant growth?
Water
Soil
(nutrients) Fertilizer
Composition
Light
Duration
Intensity
Color
These are all variables for plant growth

4. What do the variables affect?
What do those variables (water, soil, light) change?
Height
Growth Rate
Lifespan
Products (e.g. fruit)
These are all variables too

5. What is a variable? There are types of variables: Independent Variable
The variable that is changed (manipulated) by you, the scientist
the ‘I control’ variable
Dependant Variable
The result of what you changed
Depends on the independent variable

6. What is a variable? There are types of variables: Independent Variable
Changed by the scientist
An experiment usually has only one independent variable
Dependant Variable
Measured by the scientist
(what you collect data about)
Results usually come from observing dependent variables

7. Find the Variables
A study was done to find if different tire treads affect the braking distance of a car.
Independent Variable? (What is the scientist changing intentionally each time?)
Dependent Variable? (What is the scientist trying to prove?)

8. Find the Variables
Students of different ages were given the same puzzle to assemble. The puzzle assembly time was measured.
Independent Variable? (What is being changed in the experiment intentionally?)
Dependent Variable? (What is going to be affected by the change?)

9. Example – A baker
A baker wants to see if adding chocolate chips to her famous peanut butter cookies will make them sell better. So she changes the recipe and advertises her new cookies Independent Variable? (What is the baker changing intentionally in each trial?) Dependent Variable? (What result is the baker looking for?)

10. Let’s look at the results
After
# of Chips
Cookies sold 10
148 20
188 30
174 40 75
Before
# of Chips
Cookies sold
100
What do you conclude about adding chocolate chips?

11. Let’s look at the results
After
# of Chips
Cookies sold 10
148 20
188 30
174 40 75

12. Let’s try again The cookies with 0 chips are called the control group
Before
# of Chips
Cookies sold
100
After
# of Chips
Cookies sold
250 10
150 20
175
The cookies with 0 chips are called the control group

13. What variable did we miss?
A baker wants to see if adding chocolate chips to her famous peanut butter cookies will make them sell better. So she changes the recipe and advertises her new cookies Independent Variable? (What is the baker changing intentionally in each trial?) Dependent Variable? (What result is the baker looking for?)

14. Definitions Independent Variable How will you remember?
The variable that is changed by the you, the scientist
Dependant Variable
The result of what you changed

15. Remember! Your hypothesis can TELL you what your variables are!
Ex. If I drink Mountain Dew before bed, then I will not sleep very much.
IV:
DV:

16. Use this hypothesis to identify the variables:
Practice
Use this hypothesis to identify the variables:
If I leave all the lights on all day,
then my electric bill will be expensive
IV: ______________________
DV: ______________________

17. In every experiment, there are two groups:
Control
Experimental
There should be one difference
The independent variable

18. Can you conclude that the independent variable caused the dependent variable?

19. Claim: Ice cream causes sunburns
As ice cream consumption increases, so do frequency of sunburns