The Method of Science Biology Fall 2016

What is science? Science- the process that uses observation and investigation to gain knowledge about events in nature.

The Scientific Method Definitions Scientific Method- an organized set of investigation procedures used by scientists.

The Scientific Method Definitions The scientific method consists of 6 steps: Define the purpose (through observation or asking questions) Construct hypothesis Test the hypothesis Analyze the data Draw conclusions Communicate the results

The Scientific Method Definitions Hypothesis- an educated guess or testable predictions. If the water faucet is opened, then the amount of water flowing will increase. If fenders are placed on a bicycle, then the user will stay dry when going through puddles. If I raise the temperature of a cup of water, then the amount of sugar that can be dissolved in it will be increased.

The Scientific Method Definitions Experiment-organized procedure for testing a hypothesis. Place two containers of equal amounts of water, one with sugar added, into the freezer. At intervals of 30 minutes, open the freezer to determine the status of each container. Continue until both have frozen. Write down the times that the containers were checked and when they each reached a fully frozen level.

The Scientific Method Definitions Control- this is your standard for comparison In an experiment in which blood pressure medication is tested, one group is given the blood pressure medication while the control group is given a placebo pill. Researchers are testing the effectiveness of a drug intended to reduce symptoms of Crohn’s disease. Many sufferers of Crohn’s disease are recruited for the effort and the group that receives the placebo is the control group. 

The Scientific Method Definitions Constant- the factor that does NOT vary in the experiment. It is the control variable, also known as the constant variable. As the name suggests, it is the variable that the scientist wants to remain the same. Often, there is more than one control or constant variable in a scientific experiment.

The Scientific Method Definitions Independent Variable- the factor that is adjusted by the experimenter If a scientist conducts an experiment to test the theory that a vitamin could extend a person’s life-expectancy, then: The independent variable is the amount of vitamin that is given to the subjects within the experiment. This is controlled by the experimenting scientist.  A scientist studies the impact of a drug on cancer. The independent variables are the administration of the drug - the dosage and the timing.

The Scientific Method Definitions Dependent Variable- Factor whose value depends on the independent variable If a scientist conducts an experiment to test the theory that a vitamin could extend a person’s life-expectancy, then: The dependent variable, or the variable being affected by the independent variable, is life span.  A scientist studies the impact of a drug on cancer. The dependent variable is the impact the drug has on cancer. 

How to Graph Independent and Dependent Variables Independent variables are graphed on the x-axis. Dependent variables are graphed on the y-axis.

The Scientific Method Definitions Scientific Law- Rule of nature that sums up related observations to describe a pattern in nature. Example: Law of Gravity

The Scientific Method Definitions Scientific Theory- The explanation based on experiments. It is the most logical explanation. Example: The Black Hole Theory

Theory vs Law- What’s the Difference? https://www.youtube.com/watch?v=Gy N2RhbhiEU