Jdurg is right, demos are a must.
I would also say that the material has to be presented in an interesting manner. That may sound like a cop-out, but let me explain. I would say the instructor needs to do the following:
- Ask questions of the class, and make sure to call on random students, not just the ones who always answer questions
- Be open to student questions, not just lecture all the way through
- Make sure demos are interspersed at appropriate moments, not just at the beginning or end of lecture
- Be energetic with voice and dynamic with movement--I had a 92 year old P-Chem professor who talked like no one else was in the room. It was like listening to a walking corpse and probably a good deal of the reason why I hate P-Chem.
- Make sure to explain things in a logical manner and do not overestimate students' grasp. Make sure you explain things in more than one manner
And for God's sake, don't use f-ing powerpoint for anything other than pictures. If you want students to write something down, then write it yourself on the board or an overhead. It paces you so that you don't go too fast. I hate courses where teachers use powerpoint with pre-typed stuff. The students lose so much information there. Almost as bad are the powerpoint lectures were the teacher has given the students handouts of the notes already. Those suck, too, because the students don't write the information down and can go to sleep much more easily.
A prof needs to hold office hours and be receptive to students. I've know profs that just scoff at students and don't care about them. It shows.
And last, try to let the students know why you're doing things. If you stand up and say "This is the way I'm teaching" then they think you're a dick. If you let them know "No, I can't regrade your test because it would be unfair to everyone else" or "I can't accept that late because there has to be a cut off point on time or no one would ever turn anything in", then they are more understanding. If you are fair and understanding with them, they will feel like they're being treated justly. I have known way too many professors who have become callous with their students because they have been innundated with the same problems over and over, and the students think of them (somewhat justifiably) as disinterested and unfair.