Warm-Up What are three science facts you can list? (SCIENCE: bio, chemistry, geology….) YOU HAVE 5 MINUTES AFTER THE BELL RINGS TO WORK ON THE WARM-UP

8/28/17 Objective: Discuss experimental design

How do we know what we know about our world? Is everything that we “know” correct? Over time, an orderly procedure has been developed to help us to answer questions about the world we live in.

Scientific Method Definition: a logical approach to solving problems. Key word: logical. The process is orderly so that it will almost always work successfully.

Essential steps to the Scientific Method 1. Ask a question. 2. Gather information 3. Develop a hypothesis. Essential steps to the Scientific Method 4. Test the hypothesis. 5. Analyze the data 6. Draw a conclusion. Does the hypothesis appear correct? NO YES Revise the hypothesis Retest the hypothesis

1. Ask a question/State the problem What is a question about the world that you want to answer? What is a problem that you want to solve? This is the first step of the scientific method. *After you identify a problem, you should research what others have found so that you do not repeat their work.

2. Gather information Research before beginning an investigation to avoid repeating an experiment.

3. Form a hypothesis Hypothesis: a testable statement, where you predict the answer to your question. The hypothesis will state what you think MIGHT be the answer to the problem or question you are investigating. Keys: A good hypothesis is testable. A good hypothesis is NOT based on opinion or feelings.

Examples of Hypotheses Students will perform better on a test if they do not sleep for 24 hours before the test. Is this a good or bad hypothesis? (Can it be disproven or proven?) It is a GOOD hypothesis because it can be tested.

Examples of Hypotheses There is gold at the center of the planet Jupiter. Is this a good or bad hypothesis? (Can it be disproven or proven?) It is a BAD hypothesis because it cannot be tested.

Examples of Hypotheses If you mix ice cream with Fritos, the result will taste good. Is this a good or bad hypothesis? (Can it be disproven or proven?) It is a BAD hypothesis because it is based on opinion, which depends on personal taste.

4. Test the Hypothesis After you have developed a good hypothesis, you need to test it. A researcher must design experiments that will support or disprove a hypothesis. The experiments should be repeatable by others.

5. Analyze data Many important discoveries have been made from unexpected results. If the data is not organized in a logical manner, incorrect conclusions can be drawn.

6. Draw a Conclusion Revise the hypothesis if it seems incorrect. After testing, the data you gather needs to be studied. Does the hypothesis seem to be correct? Or, does the data seem to indicate that the hypothesis is incorrect? Revise the hypothesis if it seems incorrect. Retest the hypothesis [using different experiments] if it seems to be correct.

Can the scientific method answer ALL questions? NO! It deals only with the natural world. It cannot answer questions about religion OR morals (right and wrong).

Experimental Design Only change ONE factor at a time. Independent variable – factor that is changed Dependent variable – what is being measured Constant – stays the same from test to test Control – test to see what happens normally; usually independent variable = 0

Analyzing an experiment More trials/subjects is better The QUESTION tells the basic parts of the experiment: How does the independent variable affect the dependent variable? Hypothesis: predicts how the i.v. will affect the d.v. Conclusion: states how i.v. affected the d.v.

Scientific Theory vs Scientific Laws Scientific theories are the prerequisite before arriving scientific laws. Scientific theories are still to be proven whereas scientific laws are already proven. Both scientific laws and theories were based on observations.

Developing our real world scientific method Directions: Individually chose an everyday situation in which you have used or could have used the scientific method. Specify what you did or thought in each step of the method. Be sure to include at least two observations, two hypothesis, two experiments, results, and conclusion. An example will be provided. If we have enough time we will share with class.

Example Observations: (a) My flashlight will not turn on when I push the on switch. (b) When I hit the side of the flashlight it turns on for a second then turns off. Hypotheses: (a) Maybe I need to replace the batteries. (b) It could be that the light bulb needs to be replaced. Experiments: (a) Replace the batteries or (b) replace the light bulb. Results: (a) When I replaced the batteries it did not turn on. (b) When I replaced the light bulb and kept the same batteries, it worked. Conclusion: The light bulb was the problem, it was burnt out and kept the flashlight from working properly