how to right thesis statement

Tip: Check your thesis:
Use your own words in thesis statements; avoid quoting. Crafting an original, insightful, and memorable thesis makes a distinct impression on a reader. You will lose credibility as a writer if you become only a mouthpiece or a copyist; you will gain credibility by grabbing the reader with your own ideas and words.

A thesis should be as clear and specific as possible. Avoid overused, general terms and abstractions. For example, “Communism collapsed in Eastern Europe because of the ruling elite’s inability to address the economic concerns of the people” is more powerful than “Communism collapsed due to societal discontent.”
A thesis should never be vague, combative or confrontational. An ineffective thesis would be, “Communism collapsed in Eastern Europe because communism is evil.” This is hard to argue (evil from whose perspective? what does evil mean?) and it is likely to mark you as moralistic and judgmental rather than rational and thorough. It also may spark a defensive reaction from readers sympathetic to communism. If readers strongly disagree with you right off the bat, they may stop reading.

The best thesis statements are concise, contentious and coherent.
The first example takes a position, but doesn’t tell the reader anything about how you will build your argument. The second example condenses the key ideas and evidence that you will use to convince your reader.

In this thesis, I have made a claim about the theme in Narnia followed by my reasoning. The broader scope of this thesis allows me to write about each of the series’ seven novels. I am no longer limited in how many body paragraphs I can logically use.

To make a peanut butter and jelly sandwich, you must procure the ingredients, find a knife, and spread the condiments.

This fragment not only announces your subject, but it focuses on one segment of the population: elementary school children. Furthermore, it raises a subject upon which reasonable people could disagree, because while most people might agree that children consume more sugar than they used to, not everyone would agree on what should be done or who should do it. You should note that this fragment is not a thesis statement because your reader doesn’t know your conclusions on the topic.

A: “Using computers in a fourth-grade class promises to improve . . .”

References:

http://writingcenter.fas.harvard.edu/pages/developing-thesis
http://www.scribbr.com/academic-essay/thesis-statement/
http://www.easybib.com/guides/how-to-write-a-strong-thesis-statement/
http://wts.indiana.edu/writing-guides/how-to-write-a-thesis-statement.html
http://www.cws.illinois.edu/workshop/writers/tips/thesis/