Read the sentence.
Identify the subject. The subject is the most important noun in the sentence, the noun that is doing something or being described. It might be a person, animal or object. The noun may have modifying adjectives, such as in the phrase, "the big, furry dog."
Find the part of the sentence that tells what the subject is doing. Isolate the action word. The action word may be an obvious verb, such as runs, throws or jumps. The action word may also be more subtle, such as helped, thought, or said. For example, in the sentence: "The big, furry dog runs," runs is the action verb.