Planning for Success

If you are waiting for success to just drop in your lap, you may be waiting for a long time. Successful people have to work at being successful. Even after achieving a degree of success, you have to keep working to maintain your current level. However, hard work is not the only pre-requisite to success. Planning makes your efforts more productive by focusing your attention on the details and directing your energy to items which you might otherwise overlook. When teaching HVACR, lab work can be chaotic. Planning helps bring the chaos under control. I will be giving a Webinar on " Tips for Running an Effective Air Conditioning Lab" Wednesday, March 30 at 3:00 PM. The webinar is free. To register, got to the following link

https://attendee.gotowebinar.com/register/8836657677340179713

Managing Large Numbers of Lab Students

The easiest way to manage your lab is to have one lab instructor for every five students. I have actually taught lab classes where we had this ratio and it was a lot of fun. We were able to spend a lot of time with each student and we were able to do things you just can’t do with larger groups. So what if you have more like 20 students per lab instructor? It is still possible to give them a good lab experience, but a lot more planning and organizing will be required up front, and there will be things that are just not practical. One management technique is to split up large groups into smaller ones and schedule them at different times, effectively making several smaller lab classes. Of course this means you must spend more time than usual since you will be repeating the lab for each group. This may not be an option for everyone depending upon the number of instructors, students, lab equipment, and available lab time. For most of us, there will come a time when we have to work with larger groups in the lab.

A common technique is to have students work in groups. I try to avoid this if possible because it often means a couple of confident students do the work and the rest of the group watches and writes down the results. In group projects, you can see the 80/20 rule at work: 80% of the work is done by 20% of the people. However, this can be managed if you know it is going to occur. Ask every member of the group a question that requires an understanding of the process. If they know they are going to be asked to perform a task or answer a question, they will at least pay more attention to what is going on.  For example, if the group is measuring the superheat on an air conditioning system you might ask different students

What is superheat?
What measurements are required?
How did you arrive at the current superheat?
What readings are necessary to use the manufacturer’s superheat charging chart?
What does the system charging chart say the superheat should be?
Compare the manufacturer’s specification to the actual operating superheat?


Some skills are so important, every student must perform them for you individually. Lighting an oxyacetylene torch is one example. An issue with large groups is simply the amount of equipment and tools available. Most of us would be hard pressed to come up with 15 oxyacetylene torch sets so that every student could have their own. Besides, I really do NOT WANT to have more than three rookies working torches at the same time. Once when I had a class of 18 students who needed to learn to braze, I worried about how I was going to teach all of them to handle an oxyacetylene torch safely. What I did was to demonstrate, as I always do and then ask questions to see what people remembered. We then went back over the procedure, paying particular attention to things that I felt they had missed the first time. Finally, I lined them up and had each student turn on the tanks, set the regulators, light the torch, adjust the flame, shut off the flame, and shut down the torch leaving it ready for the next student. If they hesitated, they repeated the process. I noticed that the students got progressively better, which was odd because the most confident students had stepped forward first. When I remarked to one student on how quickly and confidently he performed the task he replied “I saw it done 10 times before I had to do it.” In other words, the students waiting in line learned through the experience of their fellow students. This made me feel less guilty about having everyone wait in line to work with me. This method works well for procedures that can be demonstrated in a few minutes such as lighting torches, soldering, brazing, or installing gauges. If the students use their time wisely and pay attention to what is going on they will learn by watching others and everyone leaves with an important skill they did not have the day before.

Lab Magic!

Most of us think of labs as a chance for students to practice the practical application of HVAC/R skills: brazing, charging, wiring, or troubleshooting to name a few. Certainly, students must practice their practical skills in the lab. I believe that the lab can also be instrumental in teaching more abstract concepts like gas laws or ohm’s law.

I have found that most HVAC/R students are visual and tactile learners. They learn more by seeing, touching, and doing than by reading, writing, and listening. Frequently the desire “to do” is part of what motivated them to study air conditioning in the first place, as opposed to a more academic pursuit. They arrive at the HVAC/R class excited and ready “to do”, and then we provide them with an opportunity to learn gas law formulas and ohms law. Normally we teach these subjects with an extra helping of mathematical equations. The numbers in the equations are typically all presented as part of a hypothetical example or problem. For those of us with a good understanding of the theory and the concept, the meaning is clear. For students who are still trying to understand the difference between a volt, an amp, and an ohm the problem simply becomes an exercise in math. They are not really interested in math formulas, and telling them the formulas are good for them is a bit like forcing them to take their castor oil. To overcome this, get them in the lab early and use numbers from real objects.

For ohms law, have the students measure the resistance of a strip heater, measure the voltage at the source, and then have them use ohm’s law to predict the amp draw. Next, have them operate the heater and measure its amp draw. The readings won’t be perfect, but they will be close enough to get the point across. Then do the same thing with two heaters in series and then two in parallel. They can read the individual resistance of each heater and then the combined circuit resistance to show how series and parallel resistances work. The key is to have the numbers associated with something real.

Gas behavior also works well. You can talk about the boiling point being tied to the pressure all day long and not really get the point across that boiling does not have to occur at a high temperature. This is because the information contradicts the student’s life experience – the only thing they have seen boil was hot. Put water in a flask, attach the flask to a vacuum pump, and start the vacuum pump. The water will boil at room temperature. Invite the students to touch the flask and ask questions. I have yet to see anyone who does not like this experiment. It is simple, does not take a lot of equipment, and really makes an impact.

There are many other similar labs we run whose purpose is to demonstrate an important concept. Students can quickly learn fundamental electrical circuits in the lab as well. Just make sure students know not to energize any circuits before having an instructor checks them. After the students start to connect the concepts to something that is real, then they will start to ask questions. Now you can start to use hypothetical examples and the students have a mental image of a real device to give the discussion meaning.

For some more ideas about these types of labs, take a look at the Lab Manual by David Skaves. It contains an entire section of labs labeled as Properties labs. These labs teach students about physics properties that make HVAC/R work. Although this Lab Manual is written to accompany Fundamentals of HVAC/R, it works well with any text because it is organized by subject matter with sections on Fundamentals, Properties, Refrigeration, Accessories, Controls, Electricity, Maintenance, Gas Heat, Oil Heat, and Electric Heat. Each section has several labs.