English teachers have long ago known the limits of the Point Evidence Explain system. This is a superb alternative, which enables students to explore language in detail.
The trick is to encourage students to explore at different levels, stretching them to look below the surface of the iceberg / quote.
Shakespeare presents Lady Macbeth as an atypically ambitious woman through the use of "unsex me here".
This means that Lady Macbeth wants the 'Spirits' to free her from the confines of womanhood so that she may be 'cruel' and therefore help her husband to the crown.
Further evidence to support this includes "take my milk for gall" from later in the same speech.
These quotes make us think that Lady Macbeth craves the freedom experienced by men and thinks that being a woman will make her soft and nurturing instead of ambitious and ruthless. She wants to be bitter, to be angry, to not be held back by being a woman so that she may follow through with her ambitious plans.
Therefore we understand that it was restrictive to be a woman in Shakespeare's time, and that ambition and womanhood are not compatible.
This could link to Shakespeare's message that one's ambition to change the course of nature, to wish to be 'unsexed', will lead to insanity and ultimately death. This is further supported by the fact that Macbeth dies as a result of his wanting to change the natural order of the divine right of kings.