Writing a solid thesis statement is the key to writing an effective essay.

An effective thesis statement is: clear, concise and goes beyond fact and becomes an idea that needs to be supported with opinion and evidence. In other words, a thesis always makes a point (some would say an argument) that needs to be proven.

It can be helpful to know what a thesis ISN'T. A thesis is NEVER one of the examples listed below:

An announcement: In this essay I will discuss the problems this college has.
A question: What problems does this college have?
A fact or conventional wisdom (something super obvious): Exercise is good for you
Makes no point: There are good and bad things about the constitution.

Here are examples of bad thesis statements:

This essay will examine why students drop out of school. (Is an announcement & also is fact)
Why do many people suffer from depression? (Question)
Innocent men and women might have been executed. (Just a fact—needs nothing to prove it. It is also, common, conventional wisdom).
The recession of 2008 forced many people into foreclosure. (Just a fact—needs nothing to prove it. It is common, conventional wisdom).

Examples of more effective thesis statements:

Many students drop out of school because of poverty, low self-esteem, and poor role models.
Recent studies of depression suggest that it is much more closely related to physiology than scientists had previously thought.
The death penalty must be abolished.
The current foreclosure crisis can be traced to dishonest lending practices, poor government policy, and corporate greed.

The thesis test:

Is this a complete sentence (and not a question)?
Does it have an opposing argument? (Does it need proving?)
Is every word clear and unambiguous in meaning?
Is the sentence a dead end, or does it call for additional information and explanation?
Does the statement make such a large claim that you believe the writer has no hope of proving it to be true in the space of 4 to 6 pages?
What evidence will you need to see before you will believe that the thesis is true?