thesis : /noun/ the main idea, opinion, or theory of a person, group, piece of writing, or speech

statement : /noun/ something someone says or writes officially, or an action done to express an opinion

So the Thesis Statement is a statement and has to strictly remain in one sentence and needs to display or summarise your entire essay in one line.

Troubled?

Don't worry, here is how :

A Thesis Statement can be divided into three parts.

                                          ↗︎ main topic
Thesis Statement   ↦ opinion
                                           ↘︎ reason

For example :  ¹Peanut butter and Jelly Sandwiches   ²are the best types of sandwich  ³ because they are versatile, easy to make and taste good. 

¹ Peanut butter and Jelly Sandwiches is the main topic.

² are the best types of sandwich is your opinion because you are saying that they are the best types of sandwich. You could have said that they are the worst types of sandwich.

³ because  they are versatile, easy to make and taste good are your reasons.

This might not be that clear. Here is another example :

¹Competitive Environments   ²are bad for studying   ³because it may cause mental health issues which could hinder the studies of a student  ⁴and because some students concentrate more on becoming the lead than to actually learn or understand the topic.

¹ is my main topic.

² is my opinion.

³ is my first reason.

⁴ is my second reason.

And the most important points to remember while writing a Thesis Statement...

• Must remain in one sentence.
• It MUST be the last line of the INTRODUCTION.
• Thesis Statements vary with the type of essay you are writing. The type of Thesis Statement I have discussed here is the one we use for Argumentative Essays.

Next Chapter : The Title & The Introductory Paragraph