Designing Experiments Using the Scientific Method 8th Grade Physical Science Mr. R. Baptiste

Investigation Students who want to find out things as a scientist, will want to conduct a hands-on investigative experiment that is focused on learning just one thing at a time. This is essential if the results are to be trusted by the entire science community.

The Scientific Method The scientific method is a plan that is followed in performing a scientific experiment and writing up the results. The scientific method allows experiments to be duplicated and results to be communicated uniformly. In an investigation, students: Ask a testable question Research the topic Make a hypothesis about the outcome based on the research or their own knowledge Design the investigation Conduct the investigation Collect Data Make sense of the data and draw a conclusion Present their findings for peer review

What is a Testable Question? The key to a good and manageable investigation is to choose a topic of interest, then ask what is called a “testable question.” Testable questions are those that can be answered through hands-on investigation by the student. The key difference between a general interest science question and a testable question is that testable questions are always about changing one thing to see what the effect is on another thing.

The Hypothesis When preparing to do research, a scientist must form a hypothesis, which is an educated guess about a particular problem or idea, and then work to support it and prove that it is correct, or refute it and prove that it is wrong.  Whether the scientist is right or wrong is not as important as whether he or she sets up an experiment that can be repeated by other scientists, who expect to reach the same conclusion.

The Value of Variables Experiments must have the ability to be duplicated because the "answers" the scientist comes up with (whether it supports or refutes the original hypothesis) cannot become part of the knowledge base unless other scientists can perform the exact same experiment(s) and achieve the same result. A well-designed experiment needs to have an independent variable and a dependent variable. The independent variable is what the scientist manipulates in the experiment. The dependent variable changes based on how the independent variable is manipulated. Therefore, the dependent variable provides the data for the experiment.

Experiments must contain the following Steps: A scientist must keep track of the information by recording the data. The data should be presented visually, if possible, such as through a graph or table. A control must be used. That way, results can be compared to something. Conclusions must be drawn from the results.

Present their findings for peer review What do you do with the information you gather during experiments? Well, you can graph it for a visual comparison of results from two or more experiments. The independent variable from each experiment is plotted on the x-axis (the one that runs horizontally), and the dependent variable is plotted on the y-axis (the one that runs vertically). You can plot several independent variables on the same graph by using different colors or different styles of lines.