The Scientific Method – Exercise 5 SUBTITLE Learning Objectives  Describe the components of a good experimental design  Analyze the design of example experiments  Design your own experiment Introduction  What is science?   The goal of science is to investigate and understand the natural world, to explain events in the natural world, and to use those explanations to make useful predictions. A scientist collects and organizes information in a careful, orderly way, looking for patterns and connections between events.  Scientists propose explanations that can be tested by examining evidence.  Science uses the scientific method which is a method of Inquiry. Steps in the Scientific Method       Observation of a Phenomenon Design a questions about the observation* Develop a Hypothesis (postulate the answer to your questions) Design an Experiment to test your hypothesis Data Collection Analyze your data Conclusion – Accept or reject hypothesis  Retest *ALL SCIENCE BEGINS IN THE LIBRARY!  Now let’s look at your journal articles  Did your article include data?  What was the hypothesis of your article?  What do you know about the experimental design?  Did your article use inference and is inference allowed in science? Observations and Inferences  Science begins with an observation  This is the first step in the process of gathering information about events or processes in a careful, orderly way.  Data is the information gathered from making observations. Group 1 Group 2 Class 1 82 95 Class 2 76 88 Class 3 84 90 Inductive versus deductive reasoning  Both approaches that can be used to evaluate inferences.  Deductive reasoning involves starting out with a theory or general statement, then moving towards a specific conclusion.  Inductive reasoning, on the other hand, takes a series of specific observations and tries to expand them into a more general theory. Observation or Inference? Used with nails Has a distinctive odor There are two types of data: Quantitative data are: numbers and are obtained by counting or measuring. Qualitative data are: descriptions and involve characteristics that cannot be counted. Posing a Questions  Look at the data in table 5.2 (page 33)  List 4 questions that you could ask from this data set? Designing a Controlled Experiment 1. The factors in an experiment that can be changed are called variables. Some example of variables would be: changing the temperature, the amount of light present, time, concentration of solutions used. 2. A controlled experiment works with one variable at a time. If several variables were changed at the same time, the scientist would not know which variable was responsible for the observed results. 3. In a “controlled experiment” only one variable is changed at a time. All other variables should be unchanged or “controlled”. control group with an 4. An experiment is based on the comparison between a ____________ experimental group ________________. a) These two groups are identical except for one factor. b) The control group serves as the comparison. It is the same as the experiment group, except that the one variable that is being tested is removed. c) The experimental group shows the effect of the variable that is being tested. There are two variables in an experiment: a) The independent variable is the variable that is deliberately changed by the scientist. b) The dependent variable is the one observed during the experiment. The dependent variable is the data we collect during the experiment. This data is collected as a result of changing the independent variable. In Class Activities  Read Variables Constants and Controls (page 34-35)   Complete assignment titled procedure on page 35 Read the sections titled Hypothesis and Repeated Measures, Sample Size and Reproducibility  Complete example 1 (pages 36 – 37) ❖ HOMEWORK – due at the beginning of the next class period ➢ Complete example 2 and Designing Your Own Experiments (pages 37 – 39) Design your own experiments -Homework  Google the “Giant Deep Sea Isopods (Bathynomus giganteus)  Your task is to execute and design an experiment to examine their behavior   After watching the isopods describe their structure, behavior and any individuals differences you may see. Visit the website (http://oceanexplorer.noaa.gov/facts/isopod.html) and read more about the definition of isopods.   What should you do first? What questions could you pose? Design an experiment indicate the variables, controls, hypothesis and repeated measures.
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