Tuesday means….
Homework collection…
Let’s remember…
What are the (8) characteristics of living
things?
Today we are going to learn about…
THE SCIENTIFIC METHOD!
The fundamental cornerstone of ALL SCIENCE!!!
Today’s ResourcesHandout on the Scientific Method
Worksheet on the Scientific Method
Prentice-Hall p. 8 – 14, 1060 - 1063
Words we will understand by the end of today…
Observation
Inference
Hypothesis…and the Null Hypothesis
Data – quantitative and qualitative
Variables
Controlled experiment
Control group
Back to our sewer lice….With 2 colleagues, make as many observations
and inferences about your sewer lice
You have 5 minutes….
Observations Inferences
What’s the difference between an observation and an inference?
Inference: Conclusion based on evidence and reasoning
Reasoning – but not fact
Logical – but not necessarily true…
Inductive: Specific observations extrapolate to general conclusions
Deductive: General observations extrapolate to specific results…
Based on our observations, we formulate a research question
Our research question is presented as a hypothesis, based on our biological reasoning
We typically present the Null hypothesis
So why do all experiments require a hypothesis?
‘If………..then………………’
We must have a principle that we can objectively test
We generally state the Null Hypothesis for cause-and-effect relationships
Identify the experimental VARIABLES
Dependent – what you measure (X-Axis)
Independent – what you change (Y- axis)
Controlled – what remains constant
(Uncontrolled – variables which may be hard to control)
Ideally you should have all variables controlled, excepting one dependent and one independent variable
When does a hypothesis become a theory?
When a hypothesis is repeatedly confirmed by experiment and observation (USING THE SCIENTIFIC METHOD), it may become generally considered as a THEORY
THEORIES are the most reliable, rigourous, and comprehensive form of scientific knowledge
Some well known scientific theories:
Cell theory
Evolutionary theory
Theory of relativity
Climate change theory
Designing a controlled experiment
Designing a controlled experiment
1. Formulate a focused research question
2. Identify ALL of the relevant variables (independent, dependent, controlled, uncontrolled)
3. Decide how to manipulate the independent variable – range
4. Decide how many repeats of the experiment you need to do
5. Decide if you are including a control group
How much data is enough?
The classical five by five model
5 different test groups
Repeat the test on each group 5 times
Answer Q 1 – 4 on Page 2
Answer Q 1 on Page 3
Answer Q 1 on Page 4
You have 10 minutes…
1. Control Group
2. Independent Variable
3. Dependent Variable
4. What should Smithers' conclusion be?
5. How could this experiment be improved?
Smithers thinks that a special juice will increase the productivity of workers. He creates two groups of 50 workers each and assigns each group the same task (in this case, they're supposed to staple a set of papers). Group A is given the special juice to drink while they work.
Group B is not given the special juice. After an hour, Smithers counts how many stacks of papers each group has made. Group A made 1,587 stacks, Group B made 2,113 stacks.
No special juice
The juice
Number of papers stapled
Stay off the juice! (The juice doesn’t work)
Identify the-16. Control Group
17. Independent Variable
18. Dependent Variable
19. Explain whether the data supports the advertisements claims about its product.
20. Describe how Lisa would perform this experiment. Identify the control group, and the independent and dependent variables in your description.
