How does Shakespeare develop the mood of two scenes from Act 1,2 or 3 of Macbeth?
You might want to think about the way in which Shakespeare uses juxtaposition to help develop the mood of his various scenes and also to develop dramatic irony as we the audience know something that other characters remain blissfully ignorant about. This can be seen very clearly in Act I scene 5 and Act I scene 6. If we examine these two acts, we see Lady Macbeth willingly giving herself up to evil forces as she commits herself and her body to doing whatever is necessary to fulfil the prophecy that Macbeth has received. We then see them plotting to kill Duncan whilst he is staying with them in the castle the next day. She offers her husband the following advice that corresponds with appearances vs. reality:
The dark and evil mood of this scene is immediately contrasted with the pleasant mood of Act I scene 6, which has a light and pleasant mood that is completely the opposite of the scene we have just witnessed. Note how Banquo describes the scene:
This guest of summer,
The temple-haunting martlet, does approve,
By his loved mansionry, that the heaven's breath
Smells wooingly here: no jutty, frieze,
Buttress, nor coign of vantage, but this bird
Hath made his pendent bed and procreant cradle:
Where they most breed and haunt, I have observed,
The air is delicate.
This is tremendously ironic. Just as Lady Macbeth has advised her husband to mask his true thoughts with a show of love and devotion, so nature and their castle seems to be doing exactly the same thing. There is nothing from the appearance of the castle to indicate the murderous intentions of its owners, and the mood created here is one of peacefulness and tranquility as nature itself is described in terms that would never lead us to suspect the evil schemes that have been hatched here.