The essay should be a minimum of four full pages, double-spaced, more if you wish.  Choosing an interesting, rich passage or scene should make it easy to write a full essay.  You must consult the Oxford English Dictionary.  See the directions for format given on the syllabus.  When you begin your explication, make clear the Act, scene, and lines, such as III.i.30-66, which means Act III, scene i, lines 30-66.  (It can also be written as 3.1.30-66; I find it easier to read using traditional Roman numerals, but do whatever works better for you.) Then, as you quote or refer to lines in that same scene, give the line numbers parenthetically in the text of your essay:  Desdemona declares, “I saw Othello’s visage in his mind”  (251).  If you quote more than one but less than five lines together, use slashes to indicate the line endings:  “I’ll so offend to make offense a skill,  / Redeeming time when men think least I will” (220-21).  If you quote a passage of more than four lines, block indent it ten spaces and copy it precisely, line for line.  If you quote or refer to a different scene, give the entire location, as in IV.iii.33.