QUESTION: Consider the following statements: “A drop of alcohol on a lab bench disappears after 5 minutes. The drop disappeared because molecules of alcohol moved apart and spread into the entire room.” These statements, respectively, are: A. hypothesis and theory, B. observation and hypothesis C. observation and theory, D. law and theory Observation = fact (measurements, or description of what is seen, heard, touched, smelled, or tasted) Hypothesis = an tentative explanation; testable (by doing experiments). Theory = a set of assumptions (“postulates”) that serve as basis for explaining a very wide range of observations, as well as making predictions. A theory is accepted if it is consistent with everything that is known, and modified to be consistent with new information. Hypothesis is “theoretical explanation” or “theoretical prediction” Consider the following statements: “A drop of alcohol on a lab bench disappears after 5 minutes. The drop disappeared because molecules of alcohol moved apart and spread into the entire room.” These statements, respectively, are: A. hypothesis and theory, B. observation and law C. observation and theory, D. law and theory PAUSE CLICK An observation is a statement of fact. We consider something as factual if it is a description of what we see, heard, touched, smelled, tasted, or measured.) Therefore, the first sentence…. “a drop of alcohol on a lab bench disappears after five minutes” is an observation. So, choices A and D are wrong. CROSS OUT hypothesis in choice A and law in choice D. The second sentence is an attempt to explain why the drop of alcohol disappeared. CLICK A statement that attempts to explain one or more observations is called a hypothesis. Therefore, the correct answer is B. We say that a hypothesis is tentative because it is subject to testing. We conduct experiments to test a hypothesis. In case you picked choice C, you may be wondering what the distinction is between theory and hypothesis… In common everyday usage, people tend to refer to a hypothesis as a theory. In science, a theory is actually something much bigger than a hypothesis. It’s usually not possible to state a theory in one sentence. It’s a set of ideas, called postulates, that serves as a basis for explaining a very wide range of observations. The postulates of a scientific theory usually change over time as new information is uncovered. You may have heard of a hypothesis being defined as an educated guess. It is educated because it has to be based on prior knowledge --- a good hypothesis should be based on an accepted theory. You could say that a hypothesis is a theoretical explanation, or a theoretical prediction, but it’s not the theory itself. In this question, the hypothesis given is based on the atomic theory --- which consists of ideas about matter being made up of atoms and molecules and how how these atoms and molecules behave. It’s an educated guess. If you tried to explain the disappearance of the alcohol drop by saying that an invisible fairy drank it,…. That would be a wild guess, not a hypothesis. CLICK PAUSE END RECORDING

Video ID: 1-1-1 © 2008, Project VALUE (Video Assessment Library for Undergraduate Education), Department of Physical Sciences Nicholls State University Author: Glenn V. Lo Narrator: Funded by Louisiana Board of Regents Contract No. LA-DL-SELECT-13-07/08