When lecturing, you should be more interested in ensuring the students understand what you are saying than covering a specific amount of material. Even if you manage to vocalize every important piece of information about a particular subject, it is largely a wasted effort if the students are not receiving the information. Your job is not to state all relevant facts, but to communicate them to the students. It is easy for us to transmit data faster than the students can absorb it. Remember, you have seen all this information before, probably said it all before, many times. You are not having to mentally connect the facts into a logical framework because you have already done that. However, the students who are hearing it for the first time have to comprehend each statement and then tie the different statements together in some logical manner in order to really understand what they are hearing. Help them comprehend the information by including analogies, similes, and connecting statements. One of the most powerful teaching techniques is to introduce new concepts and ideas using things people already know and understand. For example, “the refrigeration system moves heat from one place to another, much like a sponge can absorb water in one place and then release it in another when you squeeze it.” Like all analogies, it is imperfect, but it starts the process of thinking about absorbing heat in one place and releasing it somewhere else. Once you get that point across you can start talking about what the refrigerant does to absorb heat. Maybe boil some water in a flask. Learning is not just collecting data, it is making mental connections between the data points to develop new concepts. This takes time. If you are talking at gigabit speed while your students are listening on dial-up, most of the information will be lost. I have been guilty of this. I can recall asking students questions at the end of a one hour lecture only to discover that they did not really understand something that I said 15 minutes into my lecture. So although I discharged my duty to cover everything, really, I just wasted everyone’s time – including mine! So when lecturing, take some time along the way to ask a few questions and engage in some dialogue with the students to make sure your message is being received. Remember, the idea is not to demonstrate your knowledge, but to help the students increase theirs.