I use this easy formula in the classroom to help students construct a thesis statement. This is also effective when tutoring students in writing.
There are 3 elements of a thesis statement
2. Why your thesis is valid
3. Your exact position
1. Your Topic: What is the general category your essay is about. (For this example we will use School.)
2. Your Position: What is the one thing about your topic that you believe to be TRUE? If you don't have a specific opinion yet, then map out your topic. (This example: Schools have too many people in them.)
3. The Qualification:
A. Is what you say always true?
B. Are there exceptions?
C. Are there good reasons your position will have a downside?
D. What reasons would your position have any problems and can you admit them up front?
(Example: Although schools of over a thousand students have flourished in America......")
4. The Reason: Why do you think your position is correct in spite of your qualification? What is the good to be gained by your position?
(Example: Small school populations lend themselves to building a good community of learners.)
5. Put them together:
Use this order - Qualification + Reason + Position
3+4+2 = Thesis
(Example - Although schools of over a thousand students have flourished in America, small school populations lend themselves to building a good community of learners, and therefore we should consider limiting school populations to a hundred.)
It's fun to try this formula a few times with some funny and ridiculous topics.