1. The Scientific Method

2. Scientific Investigation State a Question or Problem Form a Hypothesis Test the Hypothesis through Experimentation Record and Analyze Data Form a Conclusion

3. The Testable Question Before you start an experiment you must have a reason to do it. You need to have a question that can be answered through an investigation This is called a “ Testable Question. ”

4. Examples of the Testable Question Does the amount of sunlight a plant gets affect how it grows? Does the size of the hole in the bottom of a sinking water clock affect how fast it sinks? Does caffeine affect reaction time in middle school students? Which disinfectant works the best on household germs?

5. Writing a Hypothesis A hypothesis is an “ educated guess ” or prediction about the outcome of your experiment. In order to make this prediction, you must rely on your knowledge and the research which you conducted before you began planning the experiment. The hypothesis is not random and it is not simply your opinion.

6. A Well Written Hypothesis A well written hypothesis consists of an “ if ” “ then ”, “ because ” statement. The “ if ” statement contains information on what your are testing (manipulated variable), and the “ then ” statement reflects your beliefs of the outcome of the experiment (responding variable). The “ because ” part of your hypothesis states your reasoning for your prediction, based on a scientific principle.

7. Examples “ If we increase the size of a hole in the bottom of a funnel, then the funnel will sink at a faster rate because a larger hole will allow it to fill more quickly. ” “ If caffeine is increased in someone ’ s body, then their reaction time will be quicker because caffeine is a stimulant. ”

8. Writing A Procedure A procedure is a numbered list of steps that explains how to do the experiment. It is not a paragraph! You know you have written a good procedure when someone can read it and do the experiment exactly like you did. All the variables need to be identified in your procedure. It must be clear what you are testing (manipulated variable), what you must keep the same so the test is fair (controlled variables) and what you are measuring and recording as evidence (responding variable) to answer your question. The procedure must include REPEATED TRIALS so the data is reliable.

9. Conducting The Investigation It is now time to start testing your hypothesis! This is the step that we all want to jump right into. However, it is very important that we complete the previous steps first. Safety is always an issue here. Be sure to follow all lab safety procedures while conducting an investigation.

10. Recording Data All measurements in an investigation need to be recorded in a data table. The table must have a title (related to what you are measuring), and appropriate labels for the rows and columns. Sinking Time For Funnels (seconds) Trial Number 1 2 3 Avg. Number Of Washers 0 1 2 3 1109080 93.3 36314035 1217 15 12101412

11. Analyzing Your Data In order to understand and interpret you data, often you need to make a graph or chart. This step helps you see trends in the data so you can see the relationship between the manipulated and responding variables. Was there a cause and effect? Remember your labels!!

12. Types of Variables l Control variable- the factor in the experiment that does not change. It remains constant and used for comparison. l Independent Variable- the factor in the experiment that changes Dependent Variable- The factor that is measured or observed

13. Examples of Controls and Variables Example 1: 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.

14. What are the variables your experiment? l Varying the route is the independent variable. l The time it takes is the dependent variable. control variable. l Keeping the same walker throughout makes the walker a control variable.

15. Drawing Conclusions The final piece of the scientific method is drawing conclusions. In this step we answer the investigation question. We decide if our hypothesis was supported or not. We summarize our data (this is the evidence). We explain how the data supports or does not support the hypothesis. Conclusion The greater the volume of water in the mud, the greater the distance the mudflow traveled. My hypothesis was supported by the data. When 20 mL of water were added to the dirt, the mudflow traveled an average of 21 cm. When 35 mL of water were added to the dirt, the mudflow moved an average of 160 cm. The mud with 35 mL moved 139 cm farther than the mud with 20 mL of water.

16. Sharing Conclusions To make our experiment complete we must share our findings with other people. This can be through discussion or a lab report printed for a magazine. Scientists love to read about other ’ s experiments! Sinking Water Clocks

17. Pop Quiz 1. The first step in the scientific method is: A. conducting an investigation B. writing a testable question C. writing a hypothesis D. drawing conclusions

18. 2. After writing a testable question the next step is: A. write procedure and start the investigation B. analyze data, make graph and write conclusion C. gather materials D. do research and write the hypothesis

19. 3. An educated prediction about the outcome of the investigation is called a: A. guess B. hippopotamus C. hypothesis D. hyperbole

20. 4. When writing a procedure, it should: A. test only one manipulated variable B. be specific about what data should be recorded (responding variable) C. repeat trails so the data is reliable D. all of the above

21. 5. A procedure should be in _______ form. A. paragraph B. circular C. square D. list

22. 6. After writing a good procedure, you must: A. test the hypothesis through experimentation B. form a conclusion C. analyze the data D. write a hypothesis

23. 7. The ______________ variable can be manipulated and change in the experiment. A. Dependent B. Independent C. Control

24. Variable Review Identify the dependent and independent variables in each of the following experiments. l 1. Batches of seeds are soaked in salt solutions of different concentrations. Germination is counted for each batch. l 2. Guinea pigs are kept at different temperatures for 6 weeks. At the end of that time, percent weight gain is recorded. l 3. Percent absorption by a pigment is measured for red, blue, green, and yellow wavelengths of light. l 4. The height of bean plants is recorded daily for a period of two weeks.