These are facts about essay structure which you must consider when you put together your ideas into a whole, cohesive essay.
Make sure that the ideas you generated from brainstorming produced a thesis statement and topic sentence ideas which follow all of these rules.
Controlling Ideas
The term controlling idea refers to the central idea of an essay, paragraph, or example.
It might help to define some basic terms:
- Topic: a noun or noun phrase which the essay discusses
- Thesis (statement): a sentence which says something about the topic
- Topic sentence: a sentence which provides support for the thesis
- Major supporting detail: a sentence which introduces an example or explanation, supporting the topic sentence and the thesis
An example of these in one essay might be:
- Topic: My sister
- Thesis: My sister is very organized
- Topic sentence: My sister keeps a strict schedule
- Major supporting detail: My sister plans out her busy morning schedule
Notice that the major detail supports the topic sentence, and the major detail and the thesis statement both support the thesis. Everything is about the topic.
Structurally, it looks like this, with everything supporting whatever is above it:
Another way to describe controlling ideas is that they are, somewhat, like a summary of what they control. A thesis statement is like a summary of the whole essay; a topic sentence is like a summary of the paragraph; and a major supporting detail is like a summary of the example.
The Thesis Statement
The thesis statement controls the entire essay. It summarizes what they essay is about. If your thesis statement is "My dog is obedient," then everything in the essay must support that idea, either directly or indirectly.
A thesis statement should make a point. This could be an opinion, a judgment, or a fact in question.
- You should not play video games. (opinion)
- Jimmy Carter failed as a president. (judgment)
- Global warming is a serious threat. (fact in question)
A thesis statement should make a point which is not obvious; it should be something that readers do not know, and it should be something the readers may challenge.
- Movies are entertaining. (obvious)
- Modern films use anti-heroes to reflect a loss of faith in society. (not obvious)
A thesis statement should say something of importance or interest to the reader.
- New wireless technology could cause some businesses to renovate their buildings. (why should I care about that?)
- New wireless technology could make phones cheaper. (Ooohh!)
- New wireless technology could allow hackers to steal all your money. (WHAAATT!?!?!?)
A thesis statement must not be too broad nor too general for its assigned length. For example, if you must write a 1200-word essay:
- Many foods taste good. (too broad)
- My mother's casseroles are delightful. (okay)
- My mother uses basil instead of oregano in her salmon casserole. (too narrow)
A thesis statement must focus on one idea.
- My brother is courageous. (good)
- My brother is courageous and honest. (not good)
A thesis statement must be clear.
- Japan should change its policy on immigration. (unclear)
- Japan should make it easier to become a Japanese citizen. (more clear)
- American entertainment is influential. (unclear)
- American television has raised the standards for production values worldwide. (clear)
Topic Sentences
A topic sentence defines what an essay body paragraph is about. It supports the thesis statement, proving the thesis to be true. Everything in the body paragraph must support the topic sentence.
Like thesis statements, topic sentences must not be obvious; they must be relevant and interesting to the reader; they must not be too broad or too specific; and they must be clear.
Topic sentences must be equal to and different from other topic sentences in the same paragraph.
Topic sentences must be equal to each other. One should not be much more general or more specific than the others. No topic sentence should be a subset of another topic sentence.
Topic sentences must not overlap. An example or any support in one paragraph should fit only in its own paragraph, and should not be able to support more than one topic sentence idea.

Bad balance:
- Thesis: The sale of "hoverboards" should be restricted.
- TS1: Hoverboards are dangerous
- TS2: Many people have accidents using hoverboards
- TS3: People should have licenses to ride hoverboards
The first topic sentence is too broad; the second topic sentence is support for the first topic sentence, not for the thesis statement directly; and the third topic sentence is similar to the thesis—it is not support, but a slightly more specific restatement of the thesis.
Good balance:
- Thesis: The sale of "hoverboards" should be restricted.
- TS1: Hoverboards are sold mostly to young people, who use them irresponsibly
- TS2: Hoverboard accidents can be severe
- TS3: Hoverboards are poorly designed for real-life transportation needs
All three ideas are roughly equal in scope, cover separate areas of support for the thesis, and complement each other when combined.
In addition, a topic sentence must work with other topic sentences. All topic sentences together should exactly or sufficiently cover all the points necessary to explain a thesis statement. Each topic sentence must not explain anything outside the scope of the thesis statement. All the topic sentences should cover all the necessary points to prove the thesis statement to be correct, and not leave any important points uncovered.
Good balance:
- Thesis: The sale of "hoverboards" should be restricted.
- TS1: Hoverboards are sold mostly to young people, who use them irresponsibly
- TS2: Hoverboard accidents can be severe
- TS3: Hoverboards are poorly designed for real-life transportation needs
All three topic sentences are roughly equal in scope, cover different areas which do not overlap; more importantly, it would be very difficult to come up with any other reasons which are as strong as these. With these topic sentences, it seems that the argument is complete.
Under-coverage (the reasons are too specific and do not cover all areas of the argument):
- Thesis: The sale of "hoverboards" should be restricted.
- TS1: Many school dormitories have banned hoverboards (does not explain why, and does not cover all reasons why young people use the boards poorly)
- TS2: Many people break their legs using hoverboards (ignores other injuries)
- TS3: Hoverboards do not work well on streets (does not cover sidewalks, indoor areas, or other areas people use them)
In this case, you could easily add many other topic sentences which are roughly equal to the others, and cover areas not covered already.
Over-coverage (the reasons are too broad and cover areas not related to the thesis):
- Thesis: The sale of "hoverboards" should be restricted.
- TS1: Young people are too irresponsible (focuses too much on young people)
- TS2: Motorized vehicles require training to use properly (focuses on all motorized vehicles)
- TS3: Cities nowadays cannot handle unusual forms of transportation (focuses on cities, not hoverboards)
In this last case, all three topic sentences also focus on motor vehicles in general instead of hoverboards specifically. It seems that the thesis statement should be more about modern transportation or something else.
Major Supporting Details
Major supporting details should consist of an example or explanation which gives a very specific reason to believe that the topic sentence, and therefore the thesis statement, is true. In this class, we focus on giving examples.
It is not necessary to give all possible examples. An "example," after all, is when you have too many of something, and so you choose a few which are used to show what all of them are like.
Examples must be specific. The whole idea of an example is to give a specific idea of why the topic sentence is true. Examples are used to avoid statements which are too general or vague.
Examples should be about specific events that happened at specific times. If your example is about something that happens "often" or "usually," it means you are taking many examples and explaining them all at once; this means you must summarize, using only the most general points so that all events are expressed accurately. However, this means that details are lost.
Examples must be full of very specific details. You need to include vivid reports full of descriptive words (verbs which describe specific actions, nouns which make the reader understand specific objects) and sensory words (any kind of noun, verb, or modifier that conveys a sense of something seen, heard, smelled, etc. with the senses).
See the web page on body paragraphs, especially the section on minor supporting details to see examples of this.
