1. Desdemona agrees to Cassio’s case because she knows that they are close friends and due to the fact that he helped to get Desdemona and Othello together in the first place
2. When Iago say ‘ha! I like not that’ he is referring to the fact that he can see Cassio and Desdemona talking to each other. By doing this he is making Othello feel paranoid because it makes him think that they are doing something they shouldn’t instead of having a harmless conversation.
3. After Othello repeatedly urges Iago to tell him what's on his mind, Iago says "O, beware, my lord, of jealousy;/It is the green eyed monster, which doth mock / The meat it feeds on." Othello responds with ‘O misery’. By saying this Othello is showing that he has fallen out of certainty of his love to Desdemona as he describes it as a misery. This could then suggest that he wants reassurance and sympathy from Iago and also the truth to what he thinks is happening.
4. Iago says that all the women of Venice ‘dare not show their husbands; their best consciousness is not to leave’t undone, but keep’t unknown’. This is then suggesting that he sees all women to be untrustworthy as they will keep secrets from their husbands. This then reinforces the doubt Othello has at it makes him believe that it is not an uncommon situation, making him question his wife’s loyalty
5. As stated by Thomas Coryat in ‘Coryats Crudities’ the women of Venice are described as Courtezan of Venice displaying them all be to prostitutes and therefore unfaithful.
6. This contextual evidence may then influence Othello’s decision to believe Iago about being unable to trust his wife because during the 1600’s this was the way Venetian women were displayed and along with the fact that Desdemona went behind her father’s back to get married with Othello it also suggests that she would do the same to him with another man
7. Iago echoes Brabantios earlier warning to Othello by saying ‘she did deceive her father, marrying you; and when she seemed to shake, and fear your looks, she loved them most’.
8. In this statement Iago makes the statement that it is unnatural for Desdemona and Othello to be together because of his race as he takes reference to his looks and how it was something that she should fear
9. During this scene Desdemona handkerchief becomes an important piece of stage business. It is first produced as she gives it to Othello to help him with his headache.; at this point Othello drops it on the floor and Emilia picks it up so that she can give it to Iago hoping that he will give it back to her as a token of his love. She does this because Othello first gave Desdemona the handkerchief as a token of his love to her and this is all Emilia wants from Iago
10. The fact that Emilia is able to see the importance the handkerchief has to both Desdemona and Othello could be something which motivates her to take it as it is all she wants from her husband.
11. When Othello returns to the scene he warns Iago with ‘ha, ha, false to me?’ showing that he realised Iago has been lying to him
12. Iago proves to Othello that Desdemona is disloyal by saying that  “I lay with Cassio lately, And, being troubled with a ranging tooth, I could not sleep. There are a kind of men so loose of soul, That in their sleeps will mutter their affairs: One of this kind is Cassio .In sleep I heard him say ‘Sweet Desdemona, Let us be wary, let us hide our loves’; And then, sir, would he gripe and wring my hand, Cry out ‘Sweet creature!’, and then kiss me hard, As if he plucked up kisses by the roots, That grew upon my lips; then laid his leg Over my thigh, and sighed, and kissed, and then Cried ‘Cursed fate, that gave thee to the Moor!’”
13. during this scene Othello's language becomes more monosyllabic. this is to represent how Othello is become more similar to Iago showing how well he has managed to manipulate him.