My suggestions for teaching the play would have to focus inevitably on the most controversial aspect of it: the portrayal of Shylock and his status as the Other.
Shakespeare unfortunately relies to some extent on stereotypical anti-Semitic tropes in his depiction of a Jewish moneylender. In this he is similar to other writers of his time, and later. The fact that Shylock is defeated at the end of the play is, of course, a cause for rejoicing by the other characters, and Bassanio especially, with his taunts, revels in the scene. Portia in her role as the Judge demeans Shylock in the way she speaks to him.
What I would stress about the play as a whole, however, is that despite the stereotyped depiction, Shylock is also shown in a sympathetic light, at least in certain key scenes. His soliloquy "I am a Jew" is a condemnation of anti-Semitic and, by extension, all types of demeaning and racist behavior. And the attitude of the Gentile characters in the play is shown as hypocritical. Shylock mentions having been spat upon by Antonio in the Rialto, and that he "bore it with a patient shrug."
In this aspect of the play Shakespeare was progressive. We need only contrast Shylock with the purely evil Barabbas of Marlowe's The Jew of Malta to see the difference in conceptualizing the Other between Shakespeare and one of his contemporaries.