THE SCIENTIFIC METHOD

What is Scientific Inquiry? SCIENCE  Science assumes the natural world is  Consistent  Predictable  Goals of science are  To discover patterns in nature  To use knowledge to predict

Two Types of Science  PURE SCIENCE  studying things for the sake of gaining knowledge  New discoveries  APPLIED SCIENCE  The use of science in practical ways  Technology

Limitations of Science  Science cannot make value judgments  Should we use embryonic stem cells for research?  Science cannot prove something doesn’t exist (universal negative)  Are mermaids real?  Scientific investigation is as limited as the instruments we use  Can you study Pluto with binoculars?  Scientific investigation is limited by the knowledge we already have  Copernicus couldn’t prove why his theory of planetary motion was correct because calculus hadn’t been invented yet – but he was correct!

Scientific Vocabulary  Facts – things that are observable and indisputable  Data – any piece of information; usually gained through observation and experimentation  Laws – statements that describe patterns in nature with no known exceptions.  Theories – explanations usually based on evidence (may be wrong)  Models – man-made representations to help us visualize scientific concepts

Hypothesis and Theory  An idea can become a  Hypothesis – tentative or untested explanation  Theory – tested, confirmed, supported hypothesis  Scientific Method  Ask a question  Gather facts through observation  Formulate hypotheses  Test hypotheses to formulate theories  Analyze you data  Draw conclusions based on results

Science Methods  Scientific knowledge is gained through following systematic steps:  State a problem or question to be answered  Collect facts  Develop a hypothesis  Conduct experiments  Analyze data  Reexamine the hypothesis and accept, modify or reject it

Scientific Experimentation  An experiment is a controlled test to find the answer to a question.  Only one condition in an experiment is change at a time:  The conditions that affect the outcome are called variables  Independent variable – the one changes by the experimenter  Dependent Variable – the condition that changes in response to the independent variable  Factors that do not change in an experiment are called constants.

Scientific Experimentation  Experiments have two parts:  Control group – group under normal conditions (nothing unusual done to it)  Experimental group – the test group in which a variable is changed  The goal of an experiment is to predict what might happen in similar situations.

Scientific Method  QUESTION – What do you want to know?  RESEARCH – Gather information  HYPOTHESIS – An educated guess as to the answer to the question  EXPERIMENT – written and carefully followed step- by-step procedure designed to test the hypothesis  ANALYSIS – written description of information obtained and observations made during the experiment  CONCLUSION – Was the hypothesis correct or incorrect? What did you learn?

Accuracy v. Precision  ACCURACY  How close a measurement is to the true value. Ex: in target shooting a high score indicates nearness to the bull’s eye and a high degree of accuracy.  PRECISION  Degree to which several measurements provide answers very close together so you know your data is reliable. Ex: measurements of an object that are 12.01cm, 12.00cm, 11.99cm and 12.00cm are fairly precise.

Accuracy v. Precision  One can say that a measurement is accurate but not precise; precise but not accurate; neither or both. An example of bad precision and good accuracy can be: Suppose a lab refrigerator holds a constant temperature of 38.0 F. A temperature sensor is tested 10 times in the refrigerator. The temperatures from the test yield the temperatures of: 37.8, 38.3, 38.1, 38.0, 37.6, 38.2, 38.0, 38.0, 37.4, This distribution shows no impressive tendency toward a particular value (lack of precision) but each value does come close to the actual temperature (high accuracy).temperature

Accuracy v. Precision  Write a problem where measurements are:  1. precise but not accurate  2. accurate but not precise  3. neither accurate nor precise  4. both accurate and precise  Be prepared to share your problems with the class.