All ideas of tragedy refer back in some way to Aristotle’s fourth-century BCE treatise Poetics.
Individual activity: Aristotle
Read Aristotle’s remarks on tragedy, which are in section VI of the text as reproduced in translation on The Internet Classics Archive website. Think about the ways in which this description of tragedy fits, or does not fit, Macbeth and make notes.
Renaissance ideas of tragedy
It’s still a moot point how aware Shakespeare was of classical literature. Ben Jonson, who was proud of his own learning, famously said that Shakespeare had ‘small Latin and less Greek’. You can look at his poem prefaced to the First Folio of 1623 in a digital facsimile of the First Folio of Shakespeare's plays from the Bodleian Archives. Others, however, have argued for a more learned Shakespeare. Here are some contemporary views of tragedy that may also have had an impact on the writing, and reading or viewing, of Macbeth:
Optional activity: Further reading on tragedy
For more on this, read the entry on ‘Tragedy’ in The Oxford Companion to Shakespeare, and the section ‘Structure’ in Smith, The Cambridge Introduction to Shakespeare, in particular the table on p. 94. Post anything particularly useful to the Tragedy forum, and keep in your own notes.