Determine whether the word or words you are looking at contain a subject that is actively doing something. A clause is a group of words that has a subject and verb, while a phrase is a word or group of words that is missing either a subject or a verb. For example, "the dog was walking" is a clause, while "the dog" is a phrase.
Examine the words to figure out whether they could stand alone in a sentence or whether they form a clause. If the words could stand alone and create a complete sentence with punctuation, then they form an independent clause. If the words require another clause in order to form a complete thought with punctuation, then they form a dependent clause.
Recognize common prepositions when they appear at the beginning of the group of words you are studying. When a group of words begins with a preposition, the group is a prepositional phrase. Some of the most popular prepositions include: about, because, for, on, to and with.
Isolate the word and look at its spelling. Remember that adverbs typically end in "-ly." For example, the words "quickly" and "simply" are both adverbs because they are typically used to describe a verb. It is important to remember, however, that although the "-ly" pattern at the end of the word can be a good clue, not all words that end in "-ly" are adverbs and some adverbs do not end with this pattern.
Research the meaning of the word in a dictionary. You can often understand the function of a word within a sentence by understanding what it means. The dictionary will also often contain the part of speech.
Consider how the word is used within the sentence. If the word is used to describe a noun or pronoun, it's function is as an adjective. If it is used to describe another adjective or a verb, it is an adverb.