This is the standard statement you've been provided with?

This is the statement that appears in numerous dictionaries. It's a bit long for my students, but it will work. I'm going to include all three definitions: the first one you asked about, the second one that I found in several other dictionaries, and the third one that I encapsulated for ease of digestion--and my kids need ease of digestion, especially since they'll be inundated with 100 terms of a wide range of difficulty this year.

The examples, I pulled from the Web. There are probably thousands of examples I could have pulled, but these three I liked because they showed three distinct applications of dramatic irony, but all still related to the definitions.

If you know of better, more telling examples, fantastic. I'd like to have even better ones. I think the Titanic example will ring a bell with the students.

I'd also like to impress upon them that the first two definitions that are found in many dictionaries are somewhat lacking because certain characters could be well aware of situations that many other characters aren't aware of, and that the audience shares the knowledge with these characters. I believe we still have a situation of dramatic irony--as in the case of the Dostoyevsky. My kids may never read Dostoyevsky, but they'll understand the situation of money's having been planted in an innocent's pocket.