Your English teacher likely pulled that stuff out of his or her ass. I should know, I'm an English major. Pulling stuff out of our asses is what we DO.
WOW, school coming in handy!
it's James's
Anyways, my english teacher last year knew EVERTHING. The rule is that for like old heroes, legends, famous old people (ex. Hercules' , Jesus' , Zeus')
For everyone else, its apostrophe s including those ending in s.
Almost. The exception is for classical or classicising names, such as Zeus, Xerxes, etc. As I understand it, this rule would apply regardless of context.
weckart said:
I was taught that monosyllabic proper nouns ending in s got the 's as a possessive, otherwise just the apostrophe. Therefore, James's, Miles's, Jess's but Jesus', Dolores', Francis' etc. It seems to work pretty well, whatever grammatical dogma you subscribe to.
This exception applies to names of three syllables or more that are not accented on the last or penultimate syllable. I have no idea why this is, and don't adhere to this rule myself.
As noted previously, a good rule of thumb is to include the possessive s unless it's not actually spoken (classical names notwithstanding).