Question

I struggle with understanding when to use an apostrophe with singular words ending with S..
Like for example, Class or Hughes.. Would it be Class's or Class'.... Hughes's or Hughes'?

Answer 1

Both are correct. Old rules said to add the extra S, as in "class's" but now it is acceptable not to do so, as in "class'" Rules change over time. I like the old way: add the extra S.

Answer 2

I always teach students to put that extra s in there when you can hear the two s's when you pronounce the possessive.

class's (you should be able to hear it)
This is the reading class's lunchtime.

Hughes' (you don't hear the extra s)
That was Howard Hughes' tool company.