Another approach to think through might be to consider the theme or message of this excellent short story by Saki. Instead of just using the title, you might want to think about what Saki is trying to convey or celebrate in this amusing tale. For me, this text talks about the tremendous power of storytelling - the fact that the "very self-possessed young lady of fifteen" is able to trick both Mr. Nuttel and then her family in quick succession with fabulous stories without even raising a suspicion that she is fooling them to me shows that she is a master storyteller without equal. Of course, the fact is, that we as readers are taken in by Vera's first performance as well - we believe her yarn about the Open Window, and thus it is we who are as shocked as Mr. Nuttel. It is only when we find out the truth that we realise how skilfully Vera has manipulated us as she has Mr. Nuttel and her family. Therefore a statement such as "The power of storytelling" might be an alternative title to think about. This would allow you to unpack how Vera establishes that Mr. Nuttel is "vulnerable" to her skill and goes on to exploit his weakness to the utmost.