How can a student write a good thesis statement about responsibility and teen pregnancy pertaining to the development of the human brain at 16 years old?
What a thesis statement does is make some claim. In other words, while a subject is an area for discussion, a thesis is a claim about which people disagree which you set out to prove.
If what you are talking about is teens becoming parents, you have the problem that in most developed countries most educated adults agree that it is a bad idea. Thus stating that "Teens should not become parents" is a weak thesis statement because very few people would disagree with it. Teenagers who become pregnant are likely to drop out of school, hurting their ability to get good jobs, often leading to a cycle of poverty they pass down to their offspring.
Since there are, however, teens who do become parents, you might want to think about what motivates them to become parents so early and develop a thesis statement that addresses one specific aspect of this problem. Saying that the teen brain is not fully developed is true, but is unlikely to convince or appeal to most teenagers.
If you are talking directly to teens, you might start out saying something on the order of "Although you might want to start a family now, there are some good reasons why you should wait until you finish high school." Then you could talk about such issues as the stability of the relationship between the prospective parents, how babies interfere with jobs and social life, and the ease of obtaining safe and effective birth control.
A thesis statement presents the argument or position you are going to develop further in the rest of your paper. You will need to decide what you want to communicate about your subject. Your thesis statement will be one or two sentences summarizing your topic. If you are arguing that 16-year-olds cannot be expected to act responsibly because their brains have not yet developed to the point of allowing for the making of responsible decisions about how to speak and act, this is the content of your thesis statement. If you want to refine your position and argue that teens can be responsible under some circumstances but still make risky decisions because of the order in which different areas of the brain develop, which impacts how they make decisions and choices, that becomes your thesis.
A thesis statement is an important part of your essay. It is usually found in your introductory paragraph. Your introductory paragraph provides background on the subject, while your thesis statement tells readers your essay’s purpose. Think of a thesis like a road map for your readers. It tells them your main idea, and the direction you will go in your body paragraphs. You can think of your thesis using this formula:
Purpose + direction = thesis statement.
For example: Let’s say your purpose is to argue that sixteen year olds should not be given too much responsibility, and you want to support your argument by including facts about brain development and impulse control (that is the direction of your essay).
Your thesis can explicitly state its purpose and direction:
Because teenagers have limited brain function and impulse control, sixteen year olds should not be given too much responsibility.
Readers know that you are going to talk about why they should not be given responsibility, and they know your body paragraphs will include information about their brain development and impulse control. You have, in essence, shown them where they are going to go.
Your thesis can even be implied:
Sixteen year olds should not be given too much responsibility because of numerous developmental reasons.
You have told readers your argument (purpose) and that your body paragraphs will include information about teenagers and development (direction).