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You can use the scientific method to solve a problem or question. First, you must state the problem. Next, you must do some research about what is already known about this topic. Next, you will formulate a hypothesis which is an educated guess as to what you think is the solution to your problem or question. You can set up an experiment, which is a test to see whether your hypothesis is correct or not. A proper experiment has an experimental group which gets the variable you are testing and a control group, which does not get this variable. The control group is there for comparison to the experimental group and to see if something occurred or changed due to the presence of the variable you are testing. The independent variable is the variable you, the scientist manipulates. The dependent variable is what happens due to the presence of the independent variable. You can pose the following question--Do planaria worms respond to the presence of light by moving toward it? Next, you can find out some background information on the life cycle of Planaria flatworms. You next state a hypothesis. It can be, Planarias will respond negatively to the presence of light and move away from it. You will set up a controlled experiment. The variable you manipulate which is the independent variable would be the presence of light. Whether or not the Planaria moves toward or away from it is the dependent variable. You can take a petri dish, and cover half of the dish with an index card resting above it. Place the Planaria in the center of the petri dish and shine a light from above. You can observe the behavior of the worms to see if they stay in the lighted side of the dish, or try to move under the card where there is shade. A control dish would be Planaria in a petri dish without the presence of light. All other variables must be kept constant including amount of water in the dish, size of the dish, same species of worm, etc. By observing ideally a large sample of worms in both the experimental and control groups, you will be able to analyze your data to see if your hypothesis is correct or not. You will summarize the results in your conclusion at the end of the experiment and share with others your data.
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