Focus on the central meaning of the question that precedes the text. Identify if the question is negative and look for keywords like "except" in the question. A negative question is one that in some way negates the central idea of the question. For example, a question may ask, "The following answers are true except...." Negative questions ask for you to identify something that doesn't exist in the passage. In most cases, this is the easiest aspect of recognizing the central theme of a reading passage.
Scan the text and refer back to the question to find words that fit into or are logically connected to the main concept contained in the question. The central theme of the passage is likely to follow the central concept of the question.
Find key words and transitional phrases like "then," "first," "next," "after" and "finally." These words typically indicate sequence and can help you identify the order and arrangement of ideas that make up the central concept of the passage.
Read the beginning and ending of the passage repeatedly until the information is absorbed. The central theme is often contained in both parts of the passage.
Look for cause and effect phrases such as "therefore," "because" and "as a result of." These phrases will often indicate central arguments that make up the passage's main idea.