## Monday, October 26, 2009

### The Formula To Success

A problem that many students have when beginning their study of air conditioning and refrigeration is that many of the most crucial concepts are traditionally presented primarily through math formulas. Even simple concepts become confusing when they are presented using traditional algebraic formulas that assign constants and variables for each measurement. For many students, algebraic explanations become barriers to learning. Presenting the foundation science conceptually and using analogies to common life experiences helps. If students understand the basic idea, learning the math that represents the idea is easier. That is why Fundamentals of HVAC/R presents science facts conceptually, not just as math formulas.

Take gas laws for example. Relate temperature to the average speed of the molecules: higher temperatures produce faster moving molecules; lower temperatures produce slower moving molecules. Next tell students to imagine gas pressure as the force of the gas molecules colliding with the sides of the container holding them. The more collisions produce higher gas pressure; fewer collisions produce lower gas pressure. Now tie the two concepts together: when a gas is heated the molecules move faster, increasing collisions with the sides of the container which increases the gas pressure. When a gas is cooled the molecules move slower, reducing collisions with the sides of the container which reduces the gas pressure. Discuss this point and ask questions to make sure they understand. After they have grasped the pressure temperature relationship you can introduce the related formula. Understanding the concept first makes the math a little easier to grasp because they have some context to hang it on. Remember it is more important for students to understand the pressure-temperature relationship than it is for them to calculate gas law formulas. Being able to work the gas law formula is not really the goal, understanding the temperature-pressure relationship is.

However, most standardized tests in this filed still rely heavily on manipulating traditional math formulas. So we also discuss common formulas that students are likely to see in HVAC/R literature and standardized tests, like the ICE or NATE. Throughout the book, whenever a formula is introduced, we give detailed examples showing step by step how the formula is used. To make the example formulas are easy to follow they are presented in the most straight forward, uncomplicated way possible. The text also uses practical examples showing the usefulness of the formulas that are introduced. Students are more willing to make an effort learning something that has a demonstrated application. Besides discussing formulas throughout the text whenever they are relevant, Fundamentals of HVAC/R lists many useful formulas in one place: Appendix B Commonly Used HVAC/R Formulas.

A good exercise in preparation for taking an industry standardized test is for the students to look through all the formulas listed in Appendix B and make certain they understand how to apply each formula. The unit in the text where the formula is discussed is listed beside each formula. This shows students where to look for a discussion and an example problem for any particular HVAC/R formula.