If you apply for a teaching position, you can expect to be asked to do a teaching demonstration. Generally, the interviewers will ask you to treat them as if they were students--and many will act like students, too, with all the challenges that implies. When you find yourself in this situation, take it very seriously: It's often the make-or-break moment of the whole application process.
Look, anyone can say the right things during the question-and-answer portion of the interview, and anyone can put together a lesson plan. These things are not overly impressive. If you want to impress, the demo is your chance. It's your audition, your chance to show what you would actually do in front of an actual classroom. So act accordingly.
I am always amazed when an interviewee spends his or her whole teaching demonstration at the blackboard lecturing. When I'm interviewing someone, I want to know how that person will engage students. I don't care if she makes it through the whole lesson plan (or portion thereof) that she prepared for the interview; indeed, an applicant who is doing a good job probably won't get through her whole lesson: She'll be too busy answering the questions I'm peppering her with. She'll need to take a moment to alter course when she realizes that I'm just not getting it, or she'll have to remind me not to text during class.
Teaching is all about communication--about interactions. Show your interlocutors that you know how to interact.