Common Grammar Myths

The myth that you should never-end-a-sentence-with-a-preposition
Winston Churchill, former Prime Minister of England, after being scolded for ending a sentence with a preposition, said
"Madame, this is the kind of impertinence up with which I shall not put."
Why would he have created such a monstrosity except to illustrate how foolish it sounded?
Grammar gurus once decided to make English grammar follow Latin rules. Since the verb has to be at the end of every sentence in Latin, it was decided that since a preposition is an unimportant little word and cannot occupy the position of the verb in Latin sentences, this will also be applied in English.
"Where is it at" is another story. The "at" is redundant. "Where is it?" asks the question adequately.

The split infinitive "error" myth
Star Trek brought us "To boldly go where no man. . ." and with that phrase, the debate about splitting infinitives was rekindled. The concept, however, came from someone who tried to force Latin grammar (again) onto English. In many other languages, the infinitive is one word, so English, with its "to" + the verb was another problem. Sometimes it makes good sense to put a modifier between "to" and the verb (To go boldly and Boldly to go do not say it as well).

There can be an obvious problem if there are so many words between them that the meaning is lost. "To, knowing the unlikelihood of winning the lottery because of the number of tickets sold, buy tickets every week is like throwing money down a gopher hole" is a bad sentence. "To buy tickets every week, knowing the unlikelihood of winning the lottery because of the number of tickets sold, is like throwing money down a gopher hole" is a better sentence - but not because of following a "rule." It's because of putting sentence elements where they work well together. The rule, then, is split when it serves your purposes but don't worry about it otherwise.

The myth that a high grade level score on the readability statistics in Word indicates better writing.
If you want to sound more scholarly, don't try to achieve it by adding longer words to your writing. The readability index is only a measure of word length, number of words in sentences, and number of sentences per paragraph. Remember that MSWord cannot think, and the score is not based on anything qualitative. In fact, textbooks and writers say that shorter sentences usually communicate better. Since we want to articulate our ideas as clearly as possible in order to make ourselves understood, it is wise to listen to the experts.