Introduction to the Scientific Method, Theories, and Laws

Goals of Science and Biology Tools

• Goal of Science: Investigate and try to understand nature using a hypothesis, making observations with senses to collect data, questioning processes, and researching existing knowledge.

• Tools of the Biologist: Microscopes, metric system, chromatography, flasks, and beakers.

Steps of the Scientific Method

1. State the Problem: Observe/notice, collect information, perform research, and decide on an approach to solve the problem.

2. Form a Hypothesis: Make a connection or reasonable statement based on observable characteristics, usually formatted as an "IF…THEN…" statement (e.g., "If fluoride is added to water, then the number of cavities will decrease").

3. Design an Experiment: Plan an organized approach to test the hypothesis and determine the value of the dependent variable.

   • Variables: Factors that change in an experiment. Test only one dependent variable at a time.

   • Independent Variable: The "if" part manipulated by the scientist; unrelated to other factors; plotted on the $x$-axis.

   • Dependent Variable: The "then" part that depends on the outcome of the independent variable; values are unknown prior to the experiment; plotted on the $y$-axis.

   • Controlled Experiment: Formed by identifying independent and dependent variables.

   • Experimental Group: The group being tested (receives the "if" part, e.g., $50$ parrots fed a special vitamin).

   • Control Group: The group not being tested, used as a comparison (e.g., $50$ parrots fed a regular diet without the vitamin).

   • Constant: A variable or value that does not change for the duration of the experiment.

4. Collect Data: Organize data neatly in a constructed table or chart.

5. Analyze Data: Graph data to visualize numerical values and identify patterns or relationships using bar graphs, pie charts, or line graphs.

6. Draw a Conclusion: State a connection between the data and hypothesis, answering whether the hypothesis is supported or negated. This refocuses on the hypothesis and data.

Variable Relationships and Improving Experiments

• Types of Variable Relationships:

  • Direct: As $x$ increases, $y$ increases.

  • Indirect: As $x$ increases, $y$ decreases.

  • Constant: As $x$ increases, $y$ stays the same.

• Improving an Experiment:

  • Repeat the experiment multiple times.

  • Increase the sample size.

  • Control all other variables.

Theories and Scientific Laws

• Theory: Explanations supported by experimental evidence but no tangible proof (e.g., Theory of Evolution by Charles Darwin).

• Scientific Law: Summarizes natural phenomena, is always true, and can be repeated, but does not explain how they happen (e.g., Law of Gravity).