We had a traditional, old-school, masonry fireplace put in our new home and I love it. We have it lit all the time. My three primary fuel sources are great metaphors for the fuel sources we have at our disposal as presenters, teachers and trainers to set our audiences on fire: firewood, Duraflame logs and cardboard. If you want to have your group begging for more, make sure you have a good mix of all three.
Firewood - The long-lasting, primary fuel source that is the meat and potatoes of the fireplace fuel. A fire without firewood would be weak, quick or non-existent. This fuel source represents your "base content." The stuff you have studied, practiced, refined, rehearsed, massaged and delivered over and over again. This is the content you know makes a difference. It comes in many different styles (stories, activities, formulas, lists, concepts, etc.), but it is all meaningful, connective and the main reason why the audience is there in the first place. Keep stocking up on this energy-rich material.
Duraflame Logs - We are on propane and in our town you can't install a propane-fueled, open-air fireplace; primarily because, unlike natural gas, propane is not scented. It could be running and you'd never know it. So, Duraflame logs provide the chemical spark to get the fire going and the good ones provide energy to fire up those tree logs for up to four hours. This fuel source represents any material, bits, activities, etc. that serve the sole purpose of bringing energy and combustibility to the room. You can't rely solely on this fuel source (its not meaty enough), but it is necessary to get the fire burning hot in the audience and ready to receive and accept your big content. Where variety and quantity are the keys to the firewood content, you need only find two or three magic Duraflame log bits that hit a homerun every time to really take advantage of this fuel source.
Cardboard - Oh how it burns bright and hot and awesomely... but only for a few seconds. This is a totally case-by-case (no pun intended) fuel source. If we happen to have some extra boxes around, I will tear one up, use it as kindling and watch it burn! It does go hot, but quick. Cardboard represents your use of "in-the-moment" content. Examples are headlines, recent news, current audience information, something that happened earlier at the event, etc. These little tidbits have little long-term value, but can serve to peak the audience members' attention and help you kindle their desire to check in to your main message. So, watch for these, insert them where you can, but don't rely on them.
Best of luck setting fires in 2012!