This tutorial is the first lesson in a series on Psychometrics: Lesson 1.1 review of fundamentals. To begin the study of psychometrics, first we need to have an understanding of some fundamental properties. If you feel comfortable about your understanding of these key concepts, then you can skip this video and go on to lesson 1.2 or 1.3. Some of you, however, might want to take these few minutes for a quick review. By fundamental properties, I mean the following: Mass, Force, Weight, Density, and Specific Volume. In Lesson 1.2 I provide a review of pressure and enthalpy, and finally, the concepts of sensible and latent heat. Then we will proceed to the psychometrics course. First on the list of fundamental properties are mass and force. A common definition frequently given for mass is: a fundamental property of an object-- a measure of the quantity of matter an object contains. Please note that the mass of an object is not affected by any external forces placed upon it.