1.1.2 The Scientific Method

In today’s class you should learn about.. What the scientific method is and what the main steps involved are.

Homework Learn what the following mean: scientific method, hypothesis, control In homework copy Pg 9 Q16

The Scientific Method The scientific method is one method that can be used to solve a problem

1.1.2 Scientific Method Observation Hypothesis Experiment Result Conclusion Over time as the hypothesis stands up to more and more tests it becomes accepted as a theory. A hypothesis or theory is accepted as fact only on the basis that it must stand up to challenge forever more. This is because there are limitations to the Scientific Method which means it cannot prove the truth it can only prove that ideas are false. No explanation is 100% certain e.g. better instruments, or a chance discovery, or new information or a new idea could overturn the old hypothesis. Scientists constantly challenge each others work and conclusions and scientific theory changes as knowledge increases. Scientists have to be prepared to defend their work and their explanations in public. This is done in scientific journals, at conferences and on the internet. If hypothesis is supported If hypothesis is not supported Formation of Theory and then Law A new hypothesis needs to be found and tested

1. Observation You observe something using your senses. You may come up with a question that you would like to investigate. machines - which are basically extensions of those senses. Observations – all your senses. Investigate – look at the packs, reseach how mouthwashes work.

The scientist tries to explain what caused what was observed.   2. Hypothesis:  The hypothesis is an explanation for what a scientist observes. It has to be testable. .

3. Experiment You design a fair experiment to test whether your hypothesis is correct or not. You must use a control experiment The outcome must be measurable. You must do replicate experiments ( exact copies of an experiment) .

Principles of experimentation This is not a fair test because…

Control Group -no mouthwash Testing which mouthwash is better at killing bacteria on the plates. What could the control be? Control Group -no mouthwash Petri dish Bacteria grown from swab Listerine Experimental Group Wal-Mart brand

Definition : A control experiment is a standard experiment used for comparison

4. Result Record and analyze data (information gathered from an experiment).

5. Conclusion You state whether your hypothesis was correct or not Try to explain your results.

Finally 1. You Report and Publish your results. in a Journal 2. If a hypothesis is supported by many experiments it becomes known as a theory. 3. When a theory is supported over a long period of time then it becomes known as a Law or Principle.

1.1.2 Scientific Method If hypothesis is supported If hypothesis is not supported

Limitations of the Scientific Method

Today we will … Learn about How drug trial experiments work What the limits of the scientific method are

Limitations of the Scientific Method Is limited by what can be observed with our five senses. The basis of the investigation (bad design) limitations of our measurement instruments may be affected by time pressure for results e.g., what existed prior to the Big Bang and the known universe is outside of the realm of science to investigate. We cant investigate it because it was outside our time e.g., temperature

Limitations of the scientific method scientists sometimes make mistakes Interpretation of results may be affected by the emotional involvement of investigator Some problems are solved by serendipity!

Check your learning.. What is the scientific method? What are the main steps? Define Hypothesis What should be involved in a good experiment? Define control? What happens after a hypothesis is verified? Distinguish between a theory and a law Explain 3 limitations of the scientific method

Drug testing terms As with every experiment its important to Use a LARGE SAMPLE SIZE And use RANDOM SELECTION Placebo - Control used in drug testing Single blind test Either the Scientist or the test subject knows which is the real pill and which is the placebo Double blind Neither the tester nor the person being tested knows which is the real pill and which is the placebo.

Can you… Explain some of the limits of the scientific method to solve problems? Tell why the following are important Large sample size, random selection, placebos, single blind testing, double blind testing