We started, as I always do, with the foundational structure you need for really grasping anything about networks. We started with the OSI Model. ...The mere mention of which was enough to drive one of engineers from the room. Everyone seems to hate talking about the OSI model but understanding it is vital to getting networks. Considering that pretty much every networking technology or protocol in use today can be mapped to the model, I'll say that knowing the OSI model is like grammar; almost no one wants to learn it, but everyone needs it.
Or 'class' went well. Though my inner sadist kept going for about 20 minutes after my new guy's eyes glazed over. Ah well. I told him that it gets better from here. The OSI Model talk is the only one that's all theory. We'll get into more concrete stuff -- and hands-on work in short order.