Posing Questions
Scientific inquiry often begins with a problem or question about an observation. In the case of the crickets, your question might be: Does the air temperature affect the chirping of crickets? Of course, questions don't just come to you from nowhere. Instead, questions come from experiences that you have and from observations and inferences that you make. Curiosity plays a large role as well. Think of a time that you observed something unusual or unexpected. Chances are good that your curiosity sparked a number of questions. Some questions cannot be investigated by scientific inquiry. Think about the difference between the two questions below. • Does my dog eat more food than my cat? • Which makes a better pet-a cat or a dog? |
Designing an Experiment Hypotheses lead to predictions that can be tested. In this case, your prediction would be, ''If the temperature increases, crickets will chirp more frequently." To test your prediction, you will need to observe crickets at different air temperatures. All other variables, or factors that can change in an experiment, must be exactly the same. Other variables include the kind of crickets, the type of container you test them in, and the type of thermometer you use. By keeping all of these variables the same, you will know that any difference in cricket chirping must be due to temperature alone. An experiment in which only one variable is manipulated at a time is called a controlled experiment. The one variable that is purposely changed in an experiment is called the manipulated variable (also called the independent variable). In your cricket experiment, the manipulated variable is the air temperature. The factor that may change in response to the · manipulated variable is called the responding variable (also called the dependent variable). The responding variable here is the number of cricket chirps. In life science, a controlled experiment often has a control. A control is a part of the experiment to which you can compare the results of the other tests. In the control, the conditions are the same except for the manipulated variable. For the cricket experiment, you would test your control crickets at a constant temperature. That way, you can better recognize the effects of increased temperature on chirping. Another aspect of a well-designed experiment is having clear operational definitions. An operational definition is a statement that describes how to measure a variable or define a term. For example, in this experiment you would need to determine what sounds will count as a single "chirp." Collecting and Interpreting Data For your experiment, you need a data table in which to record your data. Data are the facts, figures, and other evidence gathered through observations. A data table is an organized way to collect and record observations. After the data have been collected, they need to be interpreted. A graph can help you interpret data. Graphs can reveal patterns or trends in data. Drawing Conclusions A conclusion is a summary of what you have learned from an experiment. In drawing your conclusion, you should ask yourself whether the data support the hypothesis. You also need to consider whether you collected enough data. After reviewing the data, you decide that the evidence supports your original hypothesis. You conclude that cricket chirping does increase with temperature. It's no wonder that you have trouble sleeping on those warm summer nights! Communicating An important part of scientific inquiry is communicating your results. Communicating is the sharing of ideas and experimental findings with others through writing and speaking. For example, scientists can give talks at scientific meetings and publish articles in journals and on the Internet. When scientists communicate their research, they describe the logical connections between their procedures and results. Other scientists can then repeat and build on their experiments. |
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