Is it really grammatically incorrect to start a sentence with the words mentioned below?

Starting a sentence with a conjunction is considered correct only when used for emphasis or an additional thought in referring to a previous sentence. The word 'and' is a conjunction. So are the words 'because', 'therefore' and 'however'. Starting a sentence with a conjunction is often frown upon, because it is frequently done incorrectly or of poor dialectal etiquette. Use great caution in the practice of started a sentence with a conjunction. Starting a sentence with a conjunction should never be done for an opening line or starting a paragraph, otherwise I've started a sentence with a conjunction where it is applicable and/or the useful emphasis clarifies communicated info. Here is an example: "The plans were discussed at the last city council meeting. However, there were only three members attending." Here's another:

"We received flyers notifying the staff of the business meeting and luncheon next week. And according to the discussions, the entire staff, including the custodial workers are going to be there."

And - used to connect words, phrases, or clauses

Clause:

1. Grammar. a syntactic construction containing a subject and predicate and forming part of a sentence or constituting a WHOLE SIMPLE SENTENCE.

2. a distinct article or provision in a contract, treaty, will, or other formal or legal written document.

The question really comes down to the grammatical correctness of starting a sentence with a conjunction. That has been proscribed by countless English teachers over the years, but is is as inane as the 'Never Split an Infinitive' and the 'Never End a Sentence with a Preposition' rules.

If you use a conjunction as the first word of a sentence, just look at the horrible company you would be keeping:

BUT, in a larger sense, we can not dedicate—we can not consecrate—we can not hallow—this ground. - Lincoln, Gettysburg Address

AND the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof. - Constitution of the United States, Article 4, Section 1

AND she brought forth her firstborn son and wrapped him in swaddling clothes and laid him in a manger; because there was no room for them in the inn. AND there were in the same country shepherds abiding in the field, keeping watch over their flock by night. - Holy Bible, Luke, Chapter 2, Verses 7 and 8.

So feel free to use a conjunction as the first word in a sentence every now and then. If it comes to an argument, your teacher will be on one side, while the other side will have the Bible, Thomas Jefferson, and Abraham Lincoln. No contest.

Theoretically, it may be incorrect to begin a sentence with a conjunction, such as "and", "but", or "because", but often it is used for further emphasis of a preceding sentence. Here are a few examples:

"Joe never showed up for our date last night." "And let me tell you, that's the first time I've ever been stood up."

"Dorothy made class president." "But she's not nearly as qualified as Mary is."

"I thought I would take a trip to Colorado last fall." "Because, it's the only time I get to see my favorite aunt."

Now there is an instance where you can begin a sentence with "because", that doesn't have anything to do with emphasis. It's actually an independent clause: "Because my furnace was out of order all day yesterday, I stayed at my best friend's house."

I hope this clears things up for you.

Answering the question requires consideration of two thoughts: formality and voice. In formal writing, it is never acceptable to start a sentence with either of those words, BECAUSE they are supposed to show relation between the first half of a sentence and the second half. Grammatically, it's incorrect. However, in creative writing one of the primary considerations is the author's 'voice'. If the writer is telling you a story, grammar goes out the window. His lack of grammar could be intended to show you and easy style, or a lack of education, or some other specific personality trait. Additionally, when used in dialogue, it would be very natural to begin an answer with "Because of . . . "

In short, it is incorrect usage, but can be appropriate in specific situations.

The rules are flexible. Text intended to be read, like a news report, should be arranged for the convenience of the speaker. Often that means shortening sentences to make a place to breathe, which in turn leads to starting with something unconventional.

And it is acceptable to vary sentence order, putting dependent clauses first and using forward references. Examples: Out of ammunition, he retired to cover and reloaded. His patience had long since been exhausted before Charlie reached his front porch.

Grace can trump correctness.

I have several published books to my credit, so I feel I can give you a fair answer.

Strictly speaking, using traditional grammar, you should not start a sentence with "and" or "because."

Still, if you are a very good writer (and this is why you have seen some authors doing it), it can be very effective.

I'll give you some example I made up, but they are imitations of things I've seen in good books.

"Why on earth did you do that," Dad asked. "Because I just had to."

"I went outside and killed the dog." "And how are you going to explain that to Mom?"

I think you will get the point. Those are very "real life" examples of how people talk. They make sense. They may not follow traditional grammar, but authors use them because they work.

Because there have been some very good answers already offered, I will make mine very short. And furthermore I would like to point out that a very picky and critical English professor at a well-known university once wrote an evaluation of me. In it he said that he found my use of words, my grammar and my vocabulary to be "very sophisticated and precise."

There may be some rules that state it is always incorrect, but I would tenaciously argue those rules are incorrect.

Edit coming, just had a thought.

"Because" could be used in place of "inasmuch as."

Inasmuch as there have been some very good answers already offered, I will make mine very short.

There ARE times that you can start a sentence with the word "Because"

It is NEVER ok to start a sentence with the word "And"

Your 7th grade English teacher taught you what she did as a general rule of thumb..... And here's why:

Students love to answer questions by starting with the word "Because"

Example:

A question might ask: "Why did Shelly go to fail her math test?"

The answer might say: "Because she didn't study the night before, and she never did her homework"

Out-of-context - that answer would make no sense at all. Here's another example:

If I walked up to you in the middle of the day (out of nowhere) and said "Because I have to eat first" .... Would you have any idea what I am talking about? Of course not. I have to eat before what? The sentence is incomplete - it's a dependent clause. It needs more information. It would be correct if I said, "I cannot exercise right now because I have to eat first." Now you understand what I am talking about.

Now.... There ARE times when it is ok to start a sentence with the word "Because".... But you need to make sure that you have a complete thought

For instance:

"Because the roads were to slick this winter, I had to get better tires on my car."

This is what is referred to as a "complex sentence." It has one dependent, and one independent clause. You could REVERSE the sentence and it would still make sense...

"I had to get better tires on my car because the roads were so slick this winter"

Basically... So long as you have a complete thought / a proper sentence - You can, in fact, start it with the word "because"

Because you have asked this question, I will answer. Your teacher is not entirely correct. In the previous sentence, the subordinate clause is first, so the use of Because is correct in this case, as long as there are two clauses.

And, to answer the other part of your question, no, the use of And at the beginning of a sentence like this is incorrect.

What I have been taught over the past years is that it is FROWNED upon not totally illegal though.

I remember in 8th grade that if you have no other word that could work, then you can use it, but do not make it a habit.

I hope this has made some things cleared up.

Good Luck!