Introduction for Research paper

First impressions are so important. How many times have you heard that? It is true that the first impression—whether it’s a first meeting with a person or the first sentence of a paper—sets the stage for a lasting opinion.

The introductory paragraph of any paper, long or short, should start with a sentence that piques the interest of your readers.
In a typical essay, that first sentence leads into two or three sentences that provide details about your subject or your process. All of these sentences build up to your thesis statement.
The thesis statement is the subject of much instruction and training. The entirety of your paper hangs on that sentence. But its function is to be informative and direct.
This means it’s not normally very exciting.

The introduction is the broad beginning of the paper that answers three important questions:

1. What is this?
2. Why am I reading it?
3. What do you want me to do?

You should answer these questions by doing the following:

1. Set the context – provide general information about the main idea, explaining the situation so the reader can make sense of the topic and the claims you make and support
2. State why the main idea is important – tell the reader why s/he should care and keep reading. Your goal is to create a compelling, clear, and convincing essay people will want to read and act upon
3. State your thesis/claim – compose a sentence or two stating the position you will support with logos (sound reasoning: induction, deduction), pathos (balanced emotional appeal), and ethos (author credibility).

When writing a research paper, you may need to use a more formal, less personal tone.

Your First Sentence

To get your paper off to a great start, you should try to have a first sentence that engages your reader. Think of your first sentence as a hook that draws your reader in. It is your big chance to be so clever that your reader can’t stop.

As you researched your topic, you probably discovered many interesting anecdotes, quotes, or trivial facts. This is exactly the sort of thing you should use for an engaging introduction.
Consider these ideas for creating a strong beginning.

Surprising fact: The pentagon has twice as many bathrooms as are necessary. The famous government building was constructed in the 1940s, when segregation laws required that separate bathrooms be installed for people of African descent. This building isn’t the only American icon that harkens back to this embarrassing and hurtful time in our history. Across the United States there are many examples of leftover laws and customs that reflect the racism that once permeated American society.


Quotation: Hillary Rodham Clinton once said that “There cannot be true democracy unless women's voices are heard.” In 2006, when Nancy Pelosi became the nation’s first female Speaker of the House, one woman’s voice rang out clear. With this development, democracy grew to its truest level ever in terms of women’s equality. The historical event also paved the way for Senator Clinton as she warmed her own vocal chords in preparation for a presidential race.

Finding the Hook

In each example, the first sentence draws the reader in to find out how the interesting fact leads to a point. You can use many methods to capture your reader’s interest.

Curiosity: A duck’s quack doesn’t echo. Some people might find a deep and mysterious meaning in this fact …
 
Definition: A homograph is a word with two or more pronunciations. Produce is one example …
 
Anecdote: Yesterday morning I watched as my older sister left for school with a bright white glob of toothpaste gleaming on her chin. I felt no regret at all until she stepped onto the bus …

https://owl.english.purdue.edu/owl/resource/724/1/
http://homeworktips.about.com/od/paperassignments/a/introsentence.htm