Scientific Method

1. Scientific Method

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

3. Observations • Gathered through your senses/researched • A scientist notices something in their natural world Background information

4. Observations • An observation might be noticing that many salamanders near a particular pond have curved, tails • Research may include learning about salamanders and about the area where they live.

5. Hypothesis • A suggested solution to the problem. • Must be testable • Sometimes written as If…Then… statements • Predicts an outcome Based on background information

6. 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.

7. Experiment • A procedure to test the hypothesis.

8. Remember: To be a Valid Experiment: • Two groups are required --- the control & experimental groups • There should be only one variable changed at a time • Several trials with similar results should be done

9. Data • Must be organized • Can be organized into charts, tables, or graphs • Results of the experiment • May be quantitative (numbers) or qualitative

10. Conclusion • The answer to the question based on the data obtained from the experiment • This will either support the hypothesis or cause the hypothesis to be rejected

11. Retest In order to verify the results, experiments must be retested with similar results.

12. 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

13. Scientific Method In Action The Strange Case of BeriBeri In 1887 a strange nerve disease attacked the people in the Dutch East Indies. The disease was beriberi. Symptoms of the disease included weakness and loss of appetite, victims often died of heart failure. Scientists thought the disease might be caused by bacteria. They injected chickens with bacteria from the blood of patients with beriberi. The injected chickens became sick. However, so did a group of chickens that were not injected with bacteria. One of the scientists, Dr. Eijkman, noticed something. Before the experiment, all the chickens had eaten whole-grain rice, but during the experiment, the chickens were fed polished rice. Dr. Eijkman researched this interesting case; he found that polished rice lacked thiamine, a vitamin necessary for good health.

14. Scientific Method In Action Should the hypothesis be supported or rejected What should the new Hypothesis be State the Problem What is the Hypothesis In 1887 a strange nerve disease attacked the people in the Dutch East Indies. The disease was beriberi. Symptoms of the disease included weakness and loss of appetite, victims often died of heart failure. Scientists thought the disease might be caused by bacteria. They injected chickens with bacteria from the blood of patients with beriberi. The injected chickens became sick. However, so did a group of chickens that were not injected with bacteria. One of the scientists, Dr. Eijkman, noticed something. Before the experiment, all the chickens had eaten whole-grain rice, but during the experiment, the chickens were fed polished rice. Dr. Eijkman researched this interesting case; he found that polished rice lacked thiamine, a vitamin necessary for good health.

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

16. The Control Variable • The experimenter makes a special effort to keep everything else constant • Those factors are called control variables.

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

18. 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.

19. 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.

20. Remember: To be a Valid Experiment: • Two groups are required --- the control & experimental groups • There should be only one variable changed at a time • Several trials with similar results should be done