I'm not especially fond of thesis statements and consider them more for the teacher than for the writer or the reader.  While the writers need to develop a refined understanding of the point they want to make, a flat, direct statement of that point places limits on the writing that may inhibit the ideas or the ability to manipulate the reader.  A good thesis statement, almost by definition, has a sense of completeness to it, and if I've just read the complete point, a door has closed, journey ended, inertia lost.  There's a fair chance that I'll immediately agree or disagree with the thesis, and either reaction can be a good reason to stop reading, especially when I hadn't been allowed to build any significant momentum.  What's my motivation to jump the gap into the next paragraph?  A tidy paragraph ending with a tight, precise thesis statement may look good, but if the reader stops reading, then it's a bad introduction.  Teachers wouldn't burn out nearly so fast if they encouraged students to write papers worth reading, not merely technical exercises that bore both students and teachers.

    Those of you who are already dependent upon the tidy thesis form don't need to panic.  That option will always be there if you really need it.  When I'm really stuck, there are still times when I'll write, "This paper is intended to show..." just to get a better understanding and some writing momentum.  Then I chop that opening out as quickly as possible.  In the meantime, start thinking about the introduction in more flexible terms.  What opening will best suit the essay and conditions at hand?  That's the only way to pick a good introduction, tailored to needs of the moment, nothing straight off the rack.  But that's not to say you have no guidelines.  Creating from nothing is cause for panic indeed.  Instead, think of introductions in two categories based on speed and space, an immediate introduction or a stage setting introduction.

     Somewhere far back in my education, I heard about the Classical "in media res" technique, which means starting "in the middle of the thing" or simply that there is activity right at the beginning, without explanation, and the reader is expected to piece the ideas together as they come.  In its extreme form, such a hit-the-ground-running opening can be like an action film with a chase scene, assorted explosions, and a body count before the opening credits.  You may not know the good guys from the bad guys yet, but you don't worry about it because you're already engaged, caught in the flow.  Such an opening can be useful when space or time is limited, or if you don't want to allow the reader too much time to think before springing ideas on them, catch them with their guard down.  In a sense, the suspension of disbelief can be as important for an essay as it is for a fantasy novel.  Whether you want the reader reacting in logical or emotional terms, you don't want them being overly critical at any given moment, so speed can be your friend.

     Such writing can also be quite useful on essay exams.  Students often spend so much time setting up the ideas that they have no time to expand them before the test is over.  Go straight to the core and work with it.  Of course, the trick with speed is not letting it replace quality.  Speed writing in early drafts can create very useful accidents, but by the final draft the speed requires the precision of a driver doing 120 miles per hour on the Autobahn.  The greater the speed, the tighter the focus probably needs to be.  That also means, you can't use a fancy, action-packed opening if the rest of the movie is more like an afternoon tea.  There's always someone who thinks it will help to write "SEX" in large type at the beginning of an essay, on any subject, but all you really do is annoy the readers and lose their trust. Don't cheat your readers.

    Like the rest of the writing, the introduction is flexible and will need multiple revisions, even once you have the pieces of the essay in the order you want, so don't tie yourself to a type of opening too quickly.  However, one technique for tinkering with an in your face opening is to find the "best" sentence in your draft, and put it first.  Even if you change later, this can be a great revision technique.  If the sentence is a strong one, it should influence every sentence that follows, what stays, what's cut, and what the order needs to be.  A variation on this would be to start chopping at the beginning of your essay, and keep cutting until you reach a point that would really weaken the rest of the essay. In early drafts especially, you may be able to cut the first one or two pages before it really makes a difference (though you may pull out a necessary line or word here and there).  When that happens, don't get frustrated.  It's actually a good thing and indicates that the writing is progressing, and you're developing a better eye.

     If you have time, you can use an introduction that helps develop the mood, setting, and attitude before you dive into the heart of the material.  I think of it as my "Once upon a time" opening, but the fairy tale reference isn't meant to belittle the technique.  Quite often you need to establish certain conditions, a perspective through which the ideas need to be read, before letting the reader see what's coming.  You've probably used similar techniques when talking with your parents or your friends, perhaps so they'll be more understanding when you mention the speeding ticket.  This essay starts with a variation of that idea by making a reference to newspapers first, hopefully getting a little agreement going, before referring to the regular classroom.

     I could have started with something more like, "Teaching only thesis-driven writing should be outlawed as cruel and unusual punishment."  I suspect that would lose too much of my audience, and while I think it's true, it isn't quite what this essay is about. I also could have started with, "Once upon a time, I wrote essays with tidy, proper thesis statements, and I got high grades, but I began to lose track of why I enjoyed writing.  And for a while I even quit caring and quit writing."  There's potential there, using the personal aspects more directly, and I may even develop a similar idea eventually, but it would be for a more indirect essay, more of a show don't tell, narrative style.

     As usual in writing, there are no absolutes for picking a type of introduction.  Play.  If there's one guideline to use, it's probably to write so that the reader will never stop to consider what kind of introduction you used.  The technical aspects are for the writer, but the results should be so engaging and seamless that the reader isn't aware of the effort you put into the work.  The best athletes make the effort look effortless, but that's because of the time spent training.  Sweat in the revisions so the sweat doesn't show in the final draft.