1. Scientific Method

2. Monday, 8/14/17 What do you think makes a good (valid) experiment?
Answer this question in your notebooks:
What do you think makes a good (valid) experiment?
Today: 1.) “Scientific Method” notes
Homework: 1.) Summer work due tonight by 11:59 PM
2.) Chapter 1 outline due tomorrow (Tuesday,
8/15)

3. Word of the Day Diatribe (n) A long, abusive speech or lecture.
“Upset about his demotion, Ed made an angry diatribe about his employer.”

4. Find a Partner
Decide who will be the bacterium and who will be the human

5. Inquiry Inquiry is the search for information and explanation
Scientists begin an inquiry investigation with a question
There are two main types of scientific inquiry: discovery science and hypothesis-based science 5

6. Discovery Science
Discovery science describes natural structures and processes
This approach is based on observation and the analysis of data 6

7. Types of Data Data are recorded observations or items of information
Data fall into two categories
Qualitative, or descriptions, rather than measurements
Quantitative, or recorded measurements, which are sometimes organized into tables and graphs 7

8. Induction in Discovery Science
Inductive reasoning draws conclusions through the logical process of induction
Repeated observations can lead to important generalizations
For example, “the sun always rises in the east”
Your turn…give me an example!
Starts with an observation and then forms a generalization 8

9. Deduction: The “If…Then” Logic of Hypothesis-Based Science
Deductive reasoning uses general premises to make specific predictions
For example, if organisms are made of cells (premise 1), and humans are organisms (premise 2), then humans are composed of cells (deductive prediction)
Your turn again…example? 9

11. Partner Time
Humans: describe the difference between inductive and deductive reasoning to your partner
Bacteria: Review the difference between quantitative and qualitative data

12. Steps in the Scientific Method
Observation
Hypothesis
Experiment
Data Collection
Conclusion
Retest

13. Observations Gathered through your senses
A scientist notices something in their natural world

14. Observations
An example of an observation might be noticing that many salamanders near a pond have curved, not straight, tails

15. Hypothesis A suggested solution to the problem. Must be testable
Usually written as If…Then… statements
Predicts an outcome

16. Hypothesis
An example of a hypothesis might be that the salamanders have curved tails due to a pollutant in the moist soil where they live.

17. A procedure to test the hypothesis.
Experiment
A procedure to test the hypothesis.

18. Variable – factor in the experiment that is being tested

19. Experiment
A good or “valid” experiment will only have ONE variable changed at a time!

20. Scientific Experiments Follow Rules
An experimenter changes one factor and observes or measures what happens.

21. The Control Variable
The experimenter makes a special effort to keep other factors constant so that they will not affect the outcome.
Those factors are called control variables.

22. What is the Purpose of a Control?
Controls are NOT being tested
Controls are used for COMPARISON

23. Other Variables
The factor that is changed is known as the independent variable.
The factor that is measured or observed is called the dependent variable.

24. Example of Controls & Variables
For example, suppose you want to figure out the fastest route to walk home from school.
You will try several different routes and time how long it takes you to get home by each one.
Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

25. What are the Variables in Your Experiment?
Varying the route is the independent variable
The time it takes is the dependent variable
Keeping the same walker throughout makes the walker a control variable.
What are other examples of control variables in this experiment?

26. One more thing… it is best to make several trials with the independent variable…why?

27. Remember: To be a Valid Experiment:
Two groups are required --- the control & experimental groups
What do you think the difference is between these groups?
There should be only one variable manipulated

28. Data Results of the experiment
May be quantitative (numbers) or qualitative (descriptions)

29. Data
Must be organized
Can be organized into charts, tables, or graphs

30. Conclusion
The answer to the hypothesis is based on the data obtained from the experiment

31. In order to verify the results, experiments must be retested.

32. Solving a Problem 1) Identify a Problem
2) State Observations about the problem
3) Form a Hypothesis about the problem (if…then…)
4) Design an Experiment to test the hypothesis
5) Collect Data and organize it
6) Form a Conclusion
7) Retest

33. How a Theory Develops
A hypothesis may become so well-supported, scientists consider it a theory.
Theories enable scientists to make accurate predictions about new situations
As new evidence is uncovered, a theory may be revised or replaced by a more useful explanation

34. Inferences
Scientists often draw inferences from data gathered during experiments.
Inference- conclusion made on the basis of facts and previous knowledge rather than on direct observations.
Unlike a hypothesis, an inference is not directly testable.

35. Accuracy vs Precision
Accuracy- Getting the expected number (“accepted value”)
Precision- Getting the same number multiple times

37. Validity vs. Reliability
Validity: The degree to which a test actually measures what it is designed to measure
Reliability: Repeatability of findings (consistency)