What is a thesis statement?
Why do expository writers need one?

Ask most adults, "What is a thesis statement?" and they will define a thesis sentence as a single-sentence summary of the point of a book or article. Most adults' thesis definition is predicated on the notion that a thesis is something they discover in finished writing.

If we are teaching writing to ordinary students, however, we cannot define thesis statement as a place where the writer ends up after hours of writing. In the context of the writing process for expository nonfiction, a thesis statement needs to be a starting place.

A topic could be a sentence fragment

Before we get into what is a thesis statement, we need to make sure we understand what is not a thesis statement.

First, a thesis is not a topic. I know the two terms are often used as if the terms were interchangeable, but such sloppiness causes grief for students and teachers trying to understand the complexities of writing.

If a writing topic is a sentence fragment, it is usually a noun or phrase that can substitute for a noun. For example, these are writing topics:

• tree toads
• consequences of global warming
• becoming a writer

The first requirement of a thesis statement is that it be a sentence; statement = sentence. For any of those three fragmentary topics to become a sentence, you need to add a predicate.

A topic could be a question

Topics don't have to appear as sentence fragments. They can appear in question format, such as:

• What makes tree toads able to climb trees?
• Will shore areas or inland areas suffer more from global warming?
• How do I go about becoming a writer?

The answer to any one of those questions could be a thesis statement, but the question is just a writing topic. A statement must state or assert something; asking a question is the opposite of making an assertion.

Lack of thesis leads to writing failure

Writing is supposed to transmit an idea from a writer to a reader. When the transmission fails, we usually blame the grammar, spelling, and other writing mechanics or we blame faulty development.

All too often, however, the core problem is not poor mechanics, bad organization, or lack of ideas.

Most writing failures occur because the writer didn't have start with a controlling idea.

A thesis statement can't control the essay if it doesn't appear until the essay is written, can it? That's shutting the barn door after the horse has been stolen.

Restrict the writer to one idea

The writer may have had lots of ideas — plural — but lacked one single, central, controlling idea. The controlling idea for an essay goes by the name thesis statement or thesis sentence.

What is a thesis statement? It is simply the most important element in an essay. The thesis statement captures:

• The purpose

• The content

• The tone

of the entire essay in a single sentence. It is no stretch to say that without a thesis there is no essay.

The word thesis comes from the Greek. Even today it means what it meant to Aristotle and Sophocles. A thesis is a proposition — what we might call an opinion — that is supported by a logical, reasoned discussion.

A thesis idea must be a sentence

The difficult part of writing, as anyone who has tried it knows, is getting ideas on paper. We all have far more ideas whizzing through our brains than we could ever capture on paper. If we manage to grab some of them as they fly by our consciousness, they look rather like, well, like idea fragments.

Idea fragments are not much help to writers. Writers need sentences. Even dull students know they have to have sentences to have an essay.

• Sentences connect ideas;

• Sentences reveal relationships;

• Sentences nail down flyaway thoughts.

The sooner students reach the stage of writing sentences instead of scribbling fragments, the greater their efficiency as writers.

For optimum efficiency, students should capture their idea fragments in sentence format right at the beginning of the writing process, starting with a working thesis statement.

What is a working thesis statement?

Defining a working thesis is a bit different from answering the question what is a thesis statement.

For a particular paper, the working thesis sentence should be one answer to the question, "What is a thesis statement about this topic?"

A working thesis expresses an opinion about the topic. Ideally, it also suggests the tone and audience for the proposed paper as well.

Like a published (finished) thesis statement, a working thesis has two parts:

• The topic.

• An assertion about the topic.

Together the topic and assertion compose a single declarative sentence.

The working thesis is just for the writer's use. It's not pretty or polished. It doesn't have any modifiers to soften or limit its use. The working thesis bears about the same resemblance to a published thesis as a farm pickup bears to a stretch limo.

This discussion of the answer to the question "what is a thesis statement?" will be so much hot air to students until they start writing some thesis statements of their own. They can do that easily by brainstorming.

Click to see a simple graphic organizer that helps students understand what a thesis statement is.

One of my favorite tools for teaching difficult but essential topics is informal writing. My ebook Shape Learning, Reshape Teaching illustrates the use informal writing as a teaching tool using one area of the English curriculum that gives teachers real difficulty: grammar and puncuation. If informal writing can help students learn that material well, it can help them learn anything.