Best Answer:   Make your thesis statement strong, yet concise. Here's an example:
Sorry, but the nature of a good thesis depends to a great extent on the nature of the assignment--the kind of essay you're being asked to write.
If the assignment is to write an argumentative or persuasive essay, the thesis should be a sentence that clearly states your position on the issue you're writing about.
If you're writing an extended definition, a one-sentence formal definition would be a good thesis: "A ____ is a ____ with _____." (I. e. it should put the thing being defined in its class or category and distinguish it from other members of that class.)
If you're writing a process analysis, the thesis should describe the process in one sentence--say whether it's a simple process or a complex one, or mention the number of steps, or simply say in that one sentence what it does.
If you're writing a cause-and-effect analysis, decide whether you're going to analyze the effects of one cause or the causes of one effect; then write a thesis that states what those causes or effects were or are. (Here, if you're going to discuss causes, begin the introduction by describing the existing situation, and end it with a thesis that says in one sentence why that situation came about. And if you're going to discuss effects, use the first two or three sentences
of the introduction to describe or recount the events that brought these effects about, and end the introduction with a thesis that covers all the effects you're going to discuss. It needn't mention them all specifically, but it should COVER them.)
As you've noticed, I keep saying that the thesis should be the last sentence of the introduction and that the introduction should lead up to it. The introduction should also begin with a sentence that catches the reader's attention. And the thesis should always be one sentence that states the main idea of the entire essay, just as a topic sentence does for a single paragraph.
I hope I haven't just told you things you already knew!
Edit: You asked whether the thesis has to be the last sentence of the introduction. No, it doesn't absolutely HAVE to, but I've found that it works better there than at the very beginning. Since your teacher requires it there, you may as well put up with the restriction for the next three months, but if you really want to experiment with putting it at the beginning when you have a little more flexibility, just be sure not to put too much in the rest of the introduction--save most of what you want to say for the body. And above all, be sure to put your thesis either first or last and don't bury it in the middle.
Source(s): Retired English professor