Test Your Hypothesis by Doing an Experiment: Your ...



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Experimental Design: Plan an experiment in which you can test your hypothesis.

|Test Your Hypothesis by Doing an Experiment: Your experiment tests whether your hypothesis is true or false. It is important for |

|your experiment to be a fair test. Hypothesis: The hypothesis is an "educated guess," formed as a statement, that you propose to |

|be the answer to the research question. An educated guess is based on some prior knowledge |

• Variables: You conduct a fair test by making sure that you change only one variable at a time while keeping all other conditions and variables the same. The experiment will contain an element or elements that do not change (called controlled variables or dependent variables) and elements that will change (called manipulated variables or independent variables).

Control: The control is a particular sample that is treated the same as all the rest of the samples except that it is not exposed to manipulated variables. In many experiments it is important to perform a trial with the independent variable at a special setting for comparison with the other trials. This trial is referred to as a control group. The control group consists of all those trials where you leave the independent variable in its natural state. In our example, it would be important to run some trials in which the plants get no fertilizer at all. These trials with no fertilizer provide a basis for comparison, and would insure that any changes you see when you add fertilizer are in fact caused by the fertilizer and not something else.

Materials: List all supplies and equipment.

Example:

250 ml. glass beaker

1 straw

150 ml. Lime Water

10 g. Baking Soda

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Procedure: The procedure is a somewhat detailed, step - by - step description of how you conducted your experiment. Example: "After 1 minute, I stirred in the baking soda and timed the reaction to be 45 seconds." Key Elements of the Experimental Procedure

• Description and size of all experimental and control groups, as applicable

• LOGICAL STEPS: A step-by-step list of everything you must do to perform your experiment. Think about all the steps that you will need to go through to complete your experiment, and record exactly what will need to be done in each step.

• IV:CV:The experimental procedure must tell how you will change your one and only independent variable and how you will measure that change

• DV:The experimental procedure must explain how you will measure the resulting change in the dependent variable or variables

• CV and Controls:If applicable, the experimental procedure should explain how the controlled variables will be maintained at a constant value

Repeated Trials: This is done to verify data or results. The experimental procedure should specify how many times you intend to repeat your experiment, so that you can verify that your results are reproducible. You should also repeat your experiments several times to make sure that the first results weren't just an accident. Purpose of Trials is to verify data: Every good experiment also compares different groups of trials with each other. Such a comparison helps insure that the changes you see when you change the independent variable are in fact caused by the independent variable. There are two types of trial groups: experimental groups and control groups.

The experimental group consists of the trials where you change the independent variable. For example, if your question asks whether fertilizer makes a plant grow bigger, then the experimental group consists of all trials in which the plants receive fertilizer.

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• A good experimental procedure enables someone else to duplicate your experiment exactly!

• Observation: When you interact with your experiment, you are using your senses to observe. Does it have a smell, make a noise have color, etc.?

• Collect Data: As you observe your experiment, you will need to record the progress of your experiment. Data can be whatever you observe about your experiment that may or may not change during the time of the experimentation. Examples of data are values in pH, temperature, a measurement of growth, color, distance, etc.

• Journal: All scientists keep a record of their observations in some form of a journal. The journal will begin with the date and time the experimentor collects the data. Sometimes data will include environmental values such as humidity, temperature, etc. Entries must be written clearly and with detail of description so that another scientist can read the journal, simulate the conditions of the experiment, and repeat the experiment exactly.

• Data: The data are the values written down as the experiment progresses. Examples of data entry on measuring plant growth:

|11/15/04 |Control Plant |7.4 mm |

|  |Test Plant |16.2 mm |

|  |Test Plant |24.9 mm |

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|11/22/04 |Control Plant |7.8 mm |

|  |Test Plant |15.9 mm |

|  |Test Plant |23.2 mm |

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• Charts & Graphs: When at all possible, illustrations of data are advisable. They create a professional appearance and convey a great deal of information. Examples include: Bar Graph, Pie Chart, X & Y axis Graph, Histogram, etc.

. Analyze Your Data and Draw a Conclusion: Once your experiment is complete, you collect your measurements and analyze them to see if your hypothesis is true or false. Scientists often find that their hypothesis was false, and in such cases they will construct a new hypothesis starting the entire process of the scientific method over again. Even if they find that their hypothesis was true, they may want to test it again in a new way.

Results: The results is usually in the form of a statement that explains or interprets the data. You do not go into any detail or explanations here. You simply say in words what your data is telling you. Example: "Test Plant 3 showed little difference in growth rate as compared to the Control Plant."

Conclusion: The conclusion is a summary of the research and the results of the experiment. This is where you answer your research question. You make a statement of whether your data supported your hypothesis or not. You may have data that supported part of your hypothesis and not another part. You may also have data that did not support your hypothesis at all. In this case, you may explain why the results were different.

Application: The application is how the information or knowledge gained in the experiment can be used. It is not often included in science fair projects.

Resources: One of the most important things for a student to do is recognize the people and resources used in developing and conducting the project. Name the people who offered knowledge or helped, and list the web sites, retail stores, magazines, books, computer programs, etc. that were used as sources of information or supplies.

Communicate Your Results: To complete your science fair project you will communicate your results to others in a final report and/or a display board. Professional scientists do almost exactly the same thing by publishing their final report in a scientific journal or by presenting their results on a poster at a scientific meeting.

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