What is the Scientific Method?

Transcription

1 Scientific Method

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3 What is the Scientific Method? It s a way to solve/explain a problem or natural phenomenon, while removing human bias and opinion. It is a critical procedure that allows validity and consistency in the science field.

4 The steps of the Scientific Method are: Observe & form a question Research Hypothesis Experimentation/collect & analyze data Conclusion Repeat work Peer Review Theory & Laws formed with multiple experiments

5 THINK: Observe/Form a question What do we observe? The natural world A phenomenon or event Use the observation to create question about how or why.

6 THINK Why you would need to do research before making a hypothesis? Where would you find this information?

7 Educated guess?? Hypothesis It is a tentative testable explanation. If then Write a hypothesis regarding the what color of light (red, blue, or green) will help a plant to grow the tallest.

8 Null hypothesis A hypothesis that the experimenter expects to refute. A neutral version of the research hypothesis. Scientists will show a statement to be supported or refuted. They do not prove or disprove hypotheses. Your hypothesis can not be supported unless your null hypothesis is refuted.

9 Original hypothesis is called the alternative or research hypothesis Exercise leads to weight loss Exposure to classical music increases IQ score Extroverts are healthier than introverts Sensitivity training reduces racial bias

10 The Null hypothesis (N 0 ) is the neutral version of the research hypothesis Exercise leads to weight loss Exposure to classical music increases IQ score Extroverts are healthier than introverts Sensitivity training reduces racial bias Exercise is unrelated to weight loss Exposure to classical music has no effect on IQ score Extroverts and introverts are equally healthy. Sensitivity training has no effect on racial bias

11 Both accepting or rejecting any hypothesis is a positive result. Even if the null is not refuted, the world of science has learned something new. Strictly speaking, the term failure, should only apply to errors in the experimental design, or incorrect initial assumptions.

12 One thing people usually associate science with are experiments. But, even experiments have very stringent (strict) requirements to assure they are valid. The key to good science experimentation is: 1. Make sure the experiment fits the hypothesis. 2. That there is only one variable being tested. 3. That all other items in the experiment are controlled. (Control group and constants) 4. All data is recorded, analyzed and organized for accuracy and meaning. 5. The experiment (and results) are repeatable.

13 Variables: A variable can be either dependent or independent. Independent Affects the dependent variable. The treatment, what the experimenter is doing Graphed on the x axis Dependent Is affected by the independent variable The outcome, what is being measured Graphed on the Y axis

14 Think back to your hypothesis about plants and light color In that scenario what would be a control group? Constants? IV? DV?

15 A test for the affect of amount of light on plant growth is done so growth in mm is collected every 2 days from plants both in the light directly and not in the light at all. 1) Identify the independent variable. 2) Identify the dependent variable. 3) Think of 3 constants that would be needed for an experiment like this. 4) What could your control group be? 5) Since this is the experiment, what steps occurred before this one?

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17 Graphing!! Once you have collected your data, part of analyzing is often creating a graph to you can notice trends, relationships, and overall understand what the data means. In science we will almost always use a LINE GRAPH. Other types of graphs can be effective but they are rare.

18 How to set up your graph IV is on the x axis and DV is on the Y axis. The only exception is if you are dealing with time, then that is on the x axis instead! Numbers must be evenly distributed across the axis, do not just copy your data table! Assume it is a line graph if there are numbers on both axes or there is any measurement of time involved. You must always label both axis with numbers and units. You must always put a descriptive title on your graph. If there is more than one line, make a key. Your graph should take up all available space. Don t make a tiny graph in the corner of your graph paper!

19 LET S GRAPH!!! Woohoo!!

20 Volume (ml) LET S GRAPH!!! Woohoo!! Temperature (c)

21 Volume (ml) LET S GRAPH!!! Woohoo!! The effect of temperature on volume of a liquid. Temperature (c)

22 Share with a partner What is one thing that you learned about graphing?

23 In analyzing data while comparing the relationship between our dependent and independent variables, we can determine the relationships that the numbers (values) have. They will be

24 Positive relationship (slope) Both X and Y values increase over time.

25 Negative relationship (slope) One variable is increasing and the other is decreasing.

26 Neutral relationship Y value stays constant over time.

27 Variables can be related Causation: One variable causes the other to change. Correlation: the variables both change but due to an unknown outside factor.

28 Conclusion Use reasoning to show how your data is all related and what trends you can see. You will determine if you hypothesis was supported or refuted. Give specific numerical data to support any claim that is made.

29 2 Types of reasoning 1. Inductive reasoning: conclusions based on actual experience, witness or observations. (empirical) 2. Deductive reasoning: conclusions drawn on inferences, not actual empirical evidence. Both types are valid and should be used when drawing conclusions.

30 Try these: A) Dinosaurs have scaly skin like their close relatives the reptiles. B) Water placed at different temperatures only boils at 100 degrees Celsius. C) Your mom comes home every day at 3:00PM. So, when you hear the garage door at 3:03PM, you know it is her.

31 Scientists share their experiments and findings with others to confirm outcomes. This is done in what is called double blind verification. Double blind means that conclusions and results are sent out to other scientists (who were not involved in the original work) anonymously. There are no names on the person s work or the comments received from the evaluator. This assures that no bias occurs. EX: Think about it like this; you write up a conclusion and send it to someone who knows it is your work. (They are a friend) what might happen to their evaluation of you?

32 Theory Organized system of accepted knowledge that explains a phenomena Must be: Logical Peer reviewed Public Respectful of the rules of evidence

33 Law > Theory Explain different things but same level of certainty. Often a law will explain how and a theory explains why. GRAVITY HAS A THEORY AND A LAW The law is the equation that describes the strength, distance and relationship of objects. The theory explains why things would be attracted to one another. A theory is not a guess. It will not become a law when it is proven

34 Pure Vs. Applied Science Pure Exact Science of producing scientific theories. There may be no practical usage Doing science for the sake of science Math and Theoretical Physics Applied Used to come up with answers to problems Answers a question in the natural world Driven by the need to fix a problem or change something Biology and Chemistry

35 Try These Development of String Theory Pharmaceutical research and drug testing Building different types of rocket engines in lab Using new rocket engines to travel farther into space

36 Other factors that can influence valid science: Sample size Number of trials Lack of communication Opinions/bias Cultural differences With a partner determine how each of these can influence valid science.

37 Science and it s influence Improved quality of life Increased life span Reduced disease Increase resources Expanded our knowledge of our world Increased technology