Act One of a play should accomplish two important things:

• Introduce all the main characters and give the audience some idea of what kind of people they are.
• Introduce the main problem or question of the play -- a question that the main character will grapple to solve or overcome throughout the play's events.

So, I would ask some questions that relate to these two things.  Here are some suggestions.

1. Duncan is introduced in Act I, scene ii.  What sort of king does he appear to be?
2. Why does the play open with the Weird Sisters on a battlefield?
3. What do Macbeth and Banquo make of the prophecy that they hear in Act I, scene iii?  Are their reactions similar, different?  Explain.
4. What is the problem that is presented Macbeth once he hears the Weird Sisters' prophecies for himself and Banquo?
5. Why is Lady Macbeth, a central character in the play, not introduced until near the end of Act I?
6. Why is Macduff, a central character in the play, not introduced until Act II, scene iii?

For more on the opening scenes of the play, please follow the links below.