A common problem with speakers is keeping your audience awake and engaged, especially in the classroom.  Even with an interesting subject, in a dark room with Powerpoint slides, people tend to nod off.  A couple techniques have been useful for me to combat this that are applicable to public speaking.  The first is to use real data with lots of graphs and to ask people/students to explain what they see in the graph.  The second is to pepper my talk with interactive questions, using cards to elicit responses.  The cards encourage participation and with one glance you can see if a majority are on the right track. Buzzers work as well, but cards are cheaper.  Of course, some people refuse to respond, either from fear of making a mistake or not knowing the answer.  I so like to include demonstrations of the phenomena in class.  The demonstrations get students involved.  In the classroom for revisions, I use a jeopardy game with teams of students.  The students work problems or answer, rather than me revising the material in front of a sleeping class.  The students who can’t solve the problem or know the material see that other students can, so they know what is expected.  Also, they watch the ones who can work the problems and learn how.  This helps them learn better and gives them an indication of what is important.  Additionally, it proves feedback on what they didn’t understand and I can pause the game and explain.  It also informs me what to make clearer the next time.  These techniques have helped improve both my teaching and public speaking, although they don’t work for everyone, nor are they the right style for everyone to use.  And if someone has stayed up all night for some reason, it may be impossible to keep them awake in a dark room.