Recognize that an interjection is a word or phrase that expresses emotion, interruption or exclamation. It has no grammatical connection to other words in the sentence and is set off from the other words by an exclamation point or a comma.
Look for brief, short words or phrases in what you are reading. Interjections are frequently just one word and are rarely part of a complete sentence.
Look for interjections in dialogue situations -- usually in stories or plays -- since interjections are rarely found in academic or formal writing. Watch for commas and exclamation marks that may signal the presence of an interjection, conveying some kind of emotion or response, as in the following examples.
Surprise: "Oh my! I had no idea."
Delight: "Ah, that's good."
Confusion: "Good grief! Is that true?"
Pain: "Ouch! That hurts."
Joy: "Wow! This is super!"
Command: "Move it! Now!"
Hesitation: "Umm, what was that?"