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 Resources • Handout 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….
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 • Formulate a focused research question • Identify ALL of the relevant variables (independent, dependent, controlled, uncontrolled) • Decide how to manipulate the independent variable – range • Decide how many repeats of the experiment you need to do • Decide if you are including a control group
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…
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) 1. Control Group 2. Independent Variable 3. Dependent Variable 4. What should Smithers' conclusion be? 5. How could this experiment be improved?
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.