1. Experimental Design (designing experiments)
Pg 9

2. Learning Objectives
Know the difference between Observation and Inference
Understand the following Vocabulary:
Hypothesis
Independent Variable
Dependent Variable

3. Observation: receiving knowledge of the outside world through the senses, (sight, sound, taste, touch smell) or the recording of data using scientific instruments
Inference: to reach a conclusion from facts or knowledge, to make an educated guess
What observations can you make?
What inferences can you make?

4. Inference vs. Observation
What is it that you know is happening? (observation)
What is it that you assume to be happening? (inference)

5. Inference vs. Observation
What is it that you know is happening? (observation)
What is it that you assume to be happening? (inference)

6. Hypothesis: A specific (testable/measurable) statement of the relationship among things, often taking the form of “If…. then ….” Can be seen as a specific prediction
Examples:
If plant growth is related to the type of soil is has,
then exposing plants to unhealthily soil will result in changes in plant growth.
– specific and testable
Pg 9
If skin cancer is related to ultraviolet light,
then people with a high exposure to uv-light will have a higher rates of skin cancer.
– specific and measurable

7. If the speed from gravity is related to an object’s height above ground,
then the greater the height, the faster it should travel when dropped
-specific and testable
If I eat chocolate, then I will get pimples.
- too simple
Pg 9

8. What could be Calvin’s internal hypothesis in this case?
If the amount of snow compaction is related to the length that a snowball travels, then rolling a snowball down a long hill should be enough to knock down the neighbor girl – specific and testable (poor Suzie)

9. Independent vs. Dependent Variables
Independent variable :(the Responding variable)
The factor that is being changed for your experiment on purpose
-there can only be one ASK: “What I am I making different this time”
Dependent variable :(the Manipulated Variable)
The factor that you are measuring from your experiment
- ASK: “How will I be recording my results”
Example:
Pg 9

10. If plant growth is related to the type of soil is has,
Example:
If plant growth is related to the type of soil is has,
then exposing plants to unhealthily soil will result in changes in plant growth
You would change the type of soil (making it unhealthy)
–Independent V.
You would record/measure the growth of plant ( leaves, stem) –Dependent V.

11. Controls and Constants
Control (group):
Running a parallel experiment without the independent variable, without changing what your testing. This gives a basis to compare your results.
If plant growth is related to the type of soil is has,
then exposing plants to unhealthily soil will result in changes in plant growth.

12. Run one test (experimental group) with that changes the soil
Run another test (control group) with all the same things but NO soil change
Basically this is what you expect to get normally
If plant growth is related to the type of soil is has,
then exposing plants to unhealthily soil will result in changes in plant growth.

14. Every factor in your experiment that is NOT changing
Constants:
Every factor in your experiment that is NOT changing
Ask: what you keeping the same every time?
What would you want to keep the same between the Control group & experimental group?
Plant type
Plant food
Plant’s age
Amount of water
Amount of sunshine
Place in room
Time for the experiment

15. WHAT vs. WHY
Results: This is the actual data you recorded, (w/ graphs or tables too) The results are the FACTS that came out of your experiment. Trends (like increasing\decreasing in areas) can also be stated but they must be easily seen in your data. Results are NOT your opinions of why things happened.

16. WHAT vs. WHY
Conclusion: This is where you state WHY you think things happened they way they did. You must make it clear if you think your original hypothesis was supported or rejected by the data/result you recorded (never say PROVED)
End

17. There is NO guarantee of finding what
you expected with your experiments
Revisions are a common fact
of work in science
Thomas Edison quotes...
“I have not failed, I've just found 10,000 ways that won't work.”
“Just because something doesn't do what you planned it to do, doesn't mean it's useless.”