The Scientific Method

Scientific Investigation Testable Question Writing A Hypothesis Writing A Procedure Conducting The Investigation Observations and Recording Data Analyzing Data Reaching Conclusions Sharing Results Quiz

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.”

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?

These Are Not Testable Questions Is Jerry Rice the best football player of all time? Is the cafeteria food good? Will the school be open tomorrow? You cannot answer these questions with an experiment. Opinion questions are not testable.

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.

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.

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.”

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.

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.

Sinking Time For Funnels (seconds) 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) Number Of Washers Trial Number 1 2 3 Avg. 110 90 80 93.3 1 36 31 40 35 2 12 17 17 15 3 12 10 14 12

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!!

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.

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

Quiz Directions: Answer questions on a separate sheet of paper.

1. The first step in the scientific method is:. A 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

2. Opinion questions are: A. testable B. not testable C. scientific

3. After writing a testable question the next step is:. A 3. 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

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

5. In middle school we write our hypothesis in this format, an “____, ____, ______” statement: A. here, now, there B. if, not, because C. if, then, because D. why, why not, because

6. In a well written hypothesis, the manipulated variable can be found in the “____” part of the statement. A. if B. then

7. 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

8. A procedure should be in _______ form. A. paragraph. B. circular. C 8. A procedure should be in _______ form. A. paragraph B. circular C. square D. list

9. If you have written a good procedure, someone should be able to do your experiment somewhat like you did. A. True B. False

10. After writing a good procedure, it is time to start: A. dancing B. your engines C. your investigation

Fill In The Blank 11. A ________ helps you look at data in a way that is easy to understand. It shows trends. 12. It is very important to place a _______ on the top of your graph and ________ the x axis and y axis.

13. When doing an experiment, you record your data in a _______ _________. 14. A data table must also have a ________ at the top. 15. The final part of the scientific method is making __________. This is when you answer your investigation question and determine if your hypothesis was supported or not.