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    The Scientific Method - How to Experiment
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    Scientific Method

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  • The Scientific Method

    The scientific method outlines the correct way of performing scientific experiments in order to get unbiased and reliable results.

    There are two main types of scientific experiments commonly used in science fair projects:

    The Controlled Experiment

    The purpose of a controlled science experiment is to find out what happens to something if you change something else while you keep all other things unchanged.

    Say you want to test the effect of a certain fertilizer on radish plants growth. For this you need to create two groups of radishes: the control group and the experimental group. The two groups are treated the same (irrigation, light, etc.) besides only one factor, the fertilizer in question which is applied only to the radishes belonging to the experimental group.

    The fertilizer applied is called the independent variable (independent of any experiment factor and is decided only by your free choice) whereas the result, the growth rate of the radishes in the experimental group, is called the dependent variable (the outcome depends on the independent variable).

    In an controlled experiment you can test only one independent variable. That means that you can only change one condition in your experiment. If there's more than one independent variable in an experiment it becomes flawed. If you want to test another independent variable, you'll have to conduct another experiment. For example, if in our experiment, in the experimental group, besides the fertilizer also the amount of light is not the same as in the control group then it's impossible to deduce which condition affects the radish plants growth - the fertilizer or maybe the light intensity.

    The Comparative Experiment

    The purpose of a comparative experiment is to compare the effect of two or more different things on something.

    Suppose you want to investigate the effect of irrigation method (flood, spray or drip) on the growth rate of radishes.

    In this experiment you need three experimental groups, each for every irrigation method (flood, spray or drip) and in this case you don't need a control group at all. In this experiment the irrigation method is the independent variable and the resulting growth rate of the radishes is the dependent variable. Treat each group of plants the same (light, water quantity, nutrition, cultivation, etc.) besides your independent variable - the different irrigation method.

    In an comparative experiment you can test, of course, the effect of a few independent variables but not in the same experimental group where also only one independent variable is allowed as in the case of a controlled experiment.

    The Sections of an Experimental Science Fair Project Report

    That's a general science fair project outline requested by most teachers, competitions and judges.

    Table of Contents
    List your project sections and their corresponding page numbers.

    In 300 words or less detail in brief the experiment purpose, procedures, results, and conclusions. The goal is to present the reader a quick and clear understanding of your work. In other words, a good promo that will trigger the reader to read further. That is the last part of your project that you will write.

    Research Report
    This section displays the background information you gathered from books, magazines or the Internet that helped you to understand the topic and determine the purpose and hypothesis of your experiment.

    Here you detail the problem you were trying to solve, its importance and benefits to society, to science, etc.

    Research Question
    The research question is a focused question that states what the study will investigate. A research question might be: "what is the effect of light intensity on the photosynthesis rate of tomato plants?" and not "what is the effect of light intensity on tomato plants?" which is not focused enough and it is not clear what exactly is your experiment about since "effect on tomato plants" could mean different things like taste, color, development or photosynthesis rate as in our case.

    The hypothesis gives a supposed (hypothetical) answer to the research question. In other words, the hypothesis details in short your expectations from your experiment or what are the supposed outcomes or results.

    Suppose your research question for an experiment is, "what is the effect of the irrigation method (flood, spray or drip) on the growth rate of radishes?" The hypothesis might be "drip irrigation is the best method for the growth rate of radishes" (don't say drip irrigation is the best for radishes since best can't be measured but, on the other hand, you can measure the growth rate of radishes in cm.)

    Remember, sometimes an experiment disproves the hypothesis and it doesn't mean that your project failed, it could mean that maybe you have just discovered something new (bravo!) and you can be still awarded the 1st place on the condition that your experiment is correctly performed accordingly to the scientific method principles.

    Remember that the hypothesis is a crucial element of the scientific method since the hypothesis could be proved or refuted by statistical means.

    A list of all the materials needed to perform the experiment.

    The procedure outlines how you are going to perform your experiment - controlled or comparative - and describes your dependent and independent variables, your sample, etc.

    Take in consideration the sample size of your experiment. A too small sample can result in casual results and a too big one can result in over population effects (if you experiment with plants or animals).

    In order to avoid coincidental effects on your experiment you will need to repeat your experiment a few times this procedure is called repetitions.

    Take in account time constrains. If you only have a few weeks at your disposal to perform your experiment, don't decide on a procedure that will take months to carry out.

    Write down your procedure accurately thus you, or somebody else, can follow it in order to repeat the experiment.

    Here you collect and display the data from your experiment results. Your data should be in numbers (tabulated, graphed, etc.) and not just in verbal statements. For example, don't say that the mice "seem fatter today than they did a week ago." Words like "fatter" can lead to confusion since "fatter" can mean different things to different people. You want to tell people exactly how much your mice gained. Better to say, for example, that the mice, in average, gained 12 gram in weight the last week.

    Keep all your results in one notebook (logbook / journal) for future use.

    Sometimes "results" and "conclusion" are confused, but the two are very different.

    "Results" comprise the data collected during the experiment. On the other hand the "conclusions" is what you learned from this data and what the results mean.

    In brief, you have to state whether the experiment outcomes agree with your hypothesis. If not, that's an acceptable result too, and it doesn't mean that the experiment failed (on the condition that your experiment sticks to the scientific method guidelines).

    Also consider other possible explanations for your results (desirable or undesirable). Did you unintentionally expose your plants to winds or insects or your animals to unexpected noise and other disturbances that could affect your experiment outcomes?

    It is also recommended to mention additional experiments needed in order to investigate your topic further, and also your experiment limitations if you identify such (conditions or factors that you cannot satisfactory control in an experiment).

    The "conclusions" could be regarded as a summary of your project.

    Here you list briefly in an alphabetical order the people that helped you with your project and state briefly what they did to help.

    This is an alphabetical list of sources of information (books, magazines, web sites, etc.) used by you to conduct your research and to write your report. There are a few methods to list your bibliography correctly (http://www.juliantrubin.com/schooldirectory/reference.html).

    Examples for the scientific method applied in science fair projects
    Take notice that not all sections, in both projects, follow the same pattern.

    Remark: Don't forget that the above description is relevant only for experimental projects and that the structure of the descriptive or building / engineering project is different from the experimental one because not all the components are applicable here. For example, if your topic is "what is genetic engineering?" take in account that a hypothesis is not relevant here. And the same applies for the display board, etc.

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    Last updated: June 2013
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