INQUIRY 2 SCIENTIFIC METHOD

Designing a Controlled Experiment

When scientists want to find out why something happens the way it does, they conduct an experiment. Since they want the results of the experiment to be taken seriously by other scientists, they use a universal approach to solving problems called the scientific method.

The Scientific Method

Scientist generally follow three steps when they use the scientific method. First, they pose the question that they want to answer. Next, they form a hypothesis, their explanation or guess as to what the answer will be. Then they design and conduct an experiment that will either prove or disprove their hypothesis.
Step 1: Define the Problem

Begin by posing your question very carefully and specifically so you can carry out a proper investigation. If you do not have a good background of the problem, conduct a thorough research of all relevant information available to you, including books, journals, internet...
Step 2: Formulate a Hypothesis

Your hypothesis should be formulated in such a way that it answers the question that you are about to research. For example, if the question is "What is the effect of light intensity on plant growth?", then the hypothesis can be "If light intensity is increased, then plant growth will increase".

Step 3: Design and Conduct a Controlled Experiment

In order to find out whether your hypothesis is true or false, you must test it by conducting a controlled experiment. A controlled actually consist of two experiments run side by side. One is called the control group and the other is called the experimental group. The original experiment is called the control group. The second experiment duplicates the first, except for a single factor called the experimental variable, which you purposely change. If you make sure that only one factor differs between the two experiments, you can be confident that any difference in the results is due to this experimental variable.
Lets Practice Designing a Controlled Experiment

Suppose you want test the effect of light intensity on plant growth. You want to conduct a controlled experiment to find out whether your hypothesis is true or false, so you raise two sets of plants.

Write down anything else beside light intensity that influences plant growth and make sure that these factors remain the same in both groups of plants. For example, the amount of water, the type of soil, the amount of soil, the size of the pot, the temperature are factors that can contribute to plant growth. All these factors must be the same in both groups. The only thing that can be changed in the test group is the light intensity, which is also referred to as the independent variable.

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