Introduction to Biology Chapter 1 Scientific Method

Scientific Method State the Problem/Question Gather Information /Educate Yourself Form a Hypothesis Perform Experiment Record and Analyze Data Form a Conclusion Repeat the Experiment

Designing an Experiment Start with a question or a problem. Original question may lead directly to an experiment. Sometimes the question is too broad to be tested because there are so many possible answers. The topic may need to be narrowed down.

Hypothesis A hypothesis is a proposed scientific explanation for a set of observations. Should be written as an “If, Then” statement If the (Independent Variable) is changed this way, then the (Dependent Variable) will change this way.

Designing an Experiment A carefully designed experiment can test a prediction in a reliable way, ruling out other possible explanations. As scientists plan their experimental procedures, they pay particular attention to the factors that must be controlled.

Controlling Variables Variable – a factor that can change Three kinds of variables 1. Independent (manipulated) 2. Dependent (responding) 3. Constants

Independent Variable This is the variable that the scientist purposely changes. AKA – the manipulated variable

Dependent Variable The factor that may change because of the independent variable and that scientists want to observe. AKA – responding variable

Forming Operational Definitions This is an explicit definition of a variable so that any scientist could measure or control the variable in exactly the same way. Example The bamboo will be grown in a cool environment. The bamboo will be grown in a growth chamber at 15 C.

Constant Variables Factors that a scientist purposely keeps the same. Enables researchers to conclude that changes in the dependent variable are due to changes in the independent variable.

Control Group The control group is to serve as a standard of comparison for your experiment. Usually considered normal conditions.

Record and Analyze Data Recording data must be done in a neat and organized fashion. Tables and charts should be used. A visual representation of the data usually helps pick out patterns or trends. Use graphs or charts

Drawing Conclusions Two conclusions you can draw: My hypothesis was supported…. My hypothesis was not supported A hypothesis is not proven. Evidence from the data must be provided to support the conclusion

What to do now? If your hypothesis was supported, the experiment needs to be repeated to get the same results. If your hypothesis was not supported, the hypothesis should be reworked and the experimental procedure adjusted and the experiment repeated.