1. The Scientific Method in Action

2. SCIENCE
If you don’t make mistakes, you’re doing it wrong
If you don’t correct those mistakes, you’re doing it really wrong
If you can’t admit that you’re mistaken – then you’re not doing it at all!

3. What is Science?
(verb) it is an activity carried out by scientists, with certain raw materials, purpose and methodology in order to gain knowledge
(noun) it is the result of this activity: a well-established and well-tested body of facts, laws and models that describe the natural world.

4. Science involves the critical evaluation of ideas and information
Scientists maintain a “healthy skepticism” about information and ideas
the best way to evaluate ideas is the scientific method
Only field where ideas are tested

5. Where do we get knowledge?
Acceptance of “truth”
From inherited customs, traditions
Authority figure
Trial and error
Deductive reasoning
Assumptions from existing knowledge
Uses logical arguments (If… then)

7. In God We Trust – all others must have data

8. Scientific Method
Scientific knowledge begins with an observation and a proposed explanation.
Explanation called a hypothesis
A hypothesis is testable and falsifiable
In science hypotheses are tested by using them to make predictions about the outcome of an experiment

9. Scientific Method Scientific method
More reliable for obtaining information
You can test what you believe to be true
Others can repeat your experiment
Opportunity to prove false
Follows general set of systematic procedures
Steps are followed in order to answer a research question

10. Ethics

11. The Scientific Method Observe an event.
Develop a Hypothesis which makes a prediction.
Test the prediction.
Observe the result.
Revise the hypothesis.
Repeat as needed.
A successful hypothesis becomes a Scientific Theory.
hypothesis
test

12. Scientific Method
Everyday Science
Observation
Spaghetti sauce is red.
Hypothesis (prediction)
Use tomatoes.
Test
Heat pot of tomato sauce.
Observe result
Taste the sauce - bland.
Revise hypothesis?
Use tomato sauce and garlic!
New test?
Add garlic, taste - not so bland.
Scientific Theory
Grandma’s Recipe.

13. Scientific Method
Medical Science
Observation
Patient has high cholesterol
Hypothesis (prediction)
Certain chemicals may dissolve cholesterol deposits.
Test
Give 100 patients these chemicals, give 100 patients placebo.
Observe result
Same number lower their cholesterol as placebo patients.
Revise hypothesis?
Try different combo of chemicals.
New test?
Re-run medical test. Observe results.
Scientific Theory
Lipitor reduces cholesterol.

14. How many variables do you test at one time?

15. She explains that yeast releases a gas as it feeds on sugar.
Problem/Question
John watches his grandmother bake bread. He ask his grandmother what makes the bread rise.
She explains that yeast releases a gas as it feeds on sugar.

16. Caution! Be careful how you use effect and affect.
Effect is usually a noun and affect, a verb.
“ The effect of sugar amounts on the rising of bread.”
“How does sugar affect the rising of bread?”

17. Observation/Research
John researches the areas of baking and fermentation and tries to come up with a way to test his question.
He keeps all of his information on this topic in a journal.

18. Formulate a Hypothesis
After conducting further research, he comes up with a hypothesis.
“If more sugar is added, then the bread will rise higher.”

19. Ockams Razor
It states that among competing hypotheses, the one with the fewest assumptions should be selected. Other, more complicated solutions may ultimately prove correct, but—in the absence of certainty—the fewer assumptions that are made, the better.

20. Note: These variables will be defined in the next few slides.
Hypothesis
The hypothesis is an educated guess about the relationship between the independent and dependent variables.
Note: These variables will be defined in the next few slides.

21. Problem/Question
John wonders if the amount of sugar used in the recipe will affect the size of the bread loaf?

22. Independent Variable
The independent, or manipulated variable, is a factor that’s intentionally varied by the experimenter.
John is going to use 25g., 50g., 100g., 250g., 500g. of sugar in his experiment.

23. In this case, it would be the size of the loaf of bread.
Dependent Variable
The dependent, or responding variable, is the factor that may change as a result of changes made in the independent variable.
In this case, it would be the size of the loaf of bread.

24. Control Group
In a scientific experiment, the control is the group that serves as the standard of comparison.
The control group may be a “no treatment" or an “experimenter selected” group.

25. All experiments should have a control group.
The control group is exposed to the same conditions as the experimental group, except for the variable being tested.
All experiments should have a control group.

26. Control Group
Because his grandmother always used 50g. of sugar in her recipe, John is going to use that amount in his control group.

27. Independent variable: condition or event under study (only 1 can reliably be tested at one time)
Dependent variable: condition that could change under the influence of the independent variable (what you measure)
Controlled variables: conditions which could effect the outcome of the experiment so they must be held constant between groups
This is especially important as your results have little significance without a controlled experiment. Remember, “correlation does not equal causation”
Used for comparison

28. Causation vs Correlation

29. Constants
John’s teacher reminds him to keep all other factors the same so that any observed changes in the bread can be attributed to the variation in the amount of sugar.

30. Constants
The constants in an experiment are all the factors that the experimenter attempts to keep the same.
Can you think of some constants for this experiment?

31. Constants They might include:
Other ingredients to the bread recipe, oven used, rise time, brand of ingredients, cooking time, type of pan used, air temperature and humidity where the bread was rising, oven temperature, age of the yeast…

32. John is going to test each sugar variable 3 times.
Trials
Trials refer to replicate groups that are exposed to the same conditions in an experiment.
John is going to test each sugar variable 3 times.

33. Theories and Natural Laws
Theory: a description of the world that covers a relatively large number of phenomena and has met many observational and experimental tests
Law of Nature: theory (or group of theories) that has been tested extensively and seems to apply everywhere in the universe
One test is worth a thousand expert opinions.
Bill Nye

34. Collect and Analyze Results
John comes up with a table he can use to record his data.
John gets all his materials together and carries out his experiment.

35. Size of Baked Bread (LxWxH) cm3
Size of Bread Loaf (cm3)
Trials
Amt. of Sugar (g.) 1 2 3
Average
Size (cm3) 25
768
744
761
758 50
1296
1188
1260
100
1080
1116
250
672
576
588
612
500
432
504
360
Control group

36. Collect and Analyze Results
John examines his data and notices that his control worked the best in this experiment, but not significantly better than 100g. of sugar.
John rejects his hypothesis, but decides to re-test using sugar amounts between 50g. and 100g.

37. Can you tell which group did the best?

38. Size of Baked Bread (LxWxH) cm3
Size of Bread Loaf (cm3)
Trials
Amt. of Sugar (g.) 1 2 3
Average
Size (cm3) 50
1296
1440
1344 60
1404
1380 70
1638
1560
1612 80
1332 90
1080
1200
972
1084
Control group

39. Conclusion John finds that 70g. of sugar produces the largest loaf.
His hypothesis is accepted*

40. Graphs Graphs help us visualize numerical data.
There are several different types of graphs:
–Bar graphs
–Pie graphs
–Line graphs
Candidates should be able to recognize trends in data presented in the forms of tables or in graphical form. For example, they should be able to recognize whether or not there is a relationship between two variables and to comment on this in the context of a stated hypothesis.

41. IF….THEN If = independent variable Then = dependent variable
What is being manipulated (basis of your hypothesis)
Control group: your experiment WITHOUT this group
X axis
Then = dependent variable
What you’re measuring
Y Axis

42. Qualitative vs Quantitative
Just as it’s necessary to observe, it’s also important to quantify observations in some way
For example: define “tall”

43. Bar Graphs
Bar graphs are used to show a comparison of multiple objects.

44. Pie Graphs
Pie graphs are used to compare the parts of a whole.

45. Line graphs
Line graphs are used to show the relationship between variables.

46. Right from Wrong
The theory of gravity, theory of electricity, the germ theory of disease, and the theory of evolution are tested, accepted explanations for events that occur in nature.
Theories can really never be completely proven, only disproven. When new evidence comes along, we must modify our theory or at times even get rid of it and start over again

48. The Need for Statistics
How do you tell a really odd but correct result from a WRONG result?
The simple answer is: you can never tell for certain that a given result is “wrong”. All we can do is determine whether a given result is likely or unlikely.
There are 2 ways of getting a weird statistical measurement: an unusual result from the correct theory, or a result from the wrong theory. These are indistinguishable; because of this fact, statistics is never able to discriminate between true and false with 100% certainty.

49. Reasonability
What is a “reasonable” result is subjective and arbitrary.
For most work (and for the purposes of this class), a result is said to not differ significantly from expectations if it could happen at least 1 time in 20. That is, if the difference between the observed results and the expected results is small enough that it would be seen at least 1 time in 20 over thousands of experiments, we “fail to reject” the null hypothesis.
For technical reasons, we use “fail to reject” instead of “accept”.
“1 time in 20” can be written as a probability value p = 0.05, because 1/20 = 0.05.
Another way of putting this. If your experimental results are worse than 95% of all similar results, what you measured was very unlikely.

50. Critically Thinking
Identify and evaluate premises and conclusions in an argument
Analyze conclusions based on evidence versus those based on value judgments
Assign weight to opposing viewpoints based on chains of reasoning, sources of information (reliability)
Adjust weighting depending on relevance to central issue, lack of specific evidence or contradictions