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Scientific Method A common misperception of science is that it defines “truth”.  Science is not truth, but rather it is a way of thought. It is a process.

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Presentation on theme: "Scientific Method A common misperception of science is that it defines “truth”.  Science is not truth, but rather it is a way of thought. It is a process."— Presentation transcript:

1 Scientific Method A common misperception of science is that it defines “truth”.  Science is not truth, but rather it is a way of thought. It is a process by which experimentation is used to answer questions.

2 Steps in the Scientific Method
Observation State the problem! Research Hypothesis Experiment Data Collection Conclusion Retest

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

4 State the Problem! The scientific method starts when you ask a question about something that you observe: How, What, When, Who, Which, Why, or Where? In order for the scientific method to answer the question it must be about something that you can measure (preferably with a number).

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

6 Research & Gather Information
Rather than starting from scratch in putting together a plan for answering your question, you want to be a savvy scientist. Use library and internet research to help you find the best way to do things, and ensure that you don’t repeat mistakes from the past.

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

8 Develop a Hypothesis A hypothesis is an educated guess about how things work: “If _____[I do this] _____, then _____[this]_____ will happen.“ You must state your hypothesis in a way that you can easily measure, and of course, your hypothesis should be constructed in a way to help you answer your original question.

9 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.

10 More Example Hypotheses
“If I open the faucet then it will increase the flow of water.” “Raising the temperature of a cup of water will increase the amount of sugar that dissolves.” “If a plant receives fertilizer, then it will grow to be bigger than a plant that does not receive fertilizer.”

11 Experiment A procedure to test the hypothesis.
Results will either support or not support the hypothesis.

12 A Fair Test? It is important for your experiment to be a fair test.
You conduct a fair test by making sure that you change only one factor at a time while keeping all other conditions the same. You should also repeat your experiments several times to make sure that the first results weren’t just an accident.

13 Variable – factor in the experiment that is being tested

14 A good or “valid” experiment will only have ONE variable!

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

16 Experimental Group The subjects that ARE being given the test are known as the experimental group. It is very important that the members of this group are all alike, except for one single difference (variable).

17 Control Group The subjects that are NOT being tested are known as the control group. These subjects must also be identical to those in the experimental group – but they do not receive the “treatment.”

18 What is the Purpose of a Control Group?
Controls are NOT being tested. Controls are used for COMPARISON. This helps to prove that the results shown by the experimental group are due to the “treatment.”

19 Constants The experimenter makes a special effort to keep other factors constant so that they will not effect the outcome. Those factors are called constants.

20 Other Variables The factor that is changed is known as the independent variable (should only be one). The factor that is measured or observed is called the dependent variable (often > one).

21 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.

22 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 constant.

23 Another example…. If you open a faucet (the IV), the quantity of water flowing (DV) changes in response  you observe that the water flow increases. The number of dependent variables in an experiment varies, but there is often more than one.

24 What about the control? If we want to measure how much water flow increases when we open a faucet, it is important to make sure that the water pressure (the controlled variable) is held constant.

25 One more thing… it is best to make several trials with each independent variable.

26 Remember: To be a Valid Experiment:
Two groups are required --- the control & experimental groups There should be only one variable

27 Data Results of the experiment
May be quantitative (numbers) or qualitative

28 Data Must be organized Can be organized into charts, tables, or graphs

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

30 A Final Conclusion? Experimental results do not solve the problem, once and for all. They merely support, or do not support, the original hypothesis. Scientists often find that their hypothesis was false  DOES NOT mean the experiment was a failure!

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

32 Review Communicate Your Results!
 Make a final report, which is often published or presented.  Your report must be replicable by other researchers. If they find the same results, your research grows stronger!

33 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 6) Form a Conclusion 7) Retest

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