A plural noun, including proper nouns, that ends in "s" is written thus: Edmunds'
So, one student : the student's books
two students : the students' books
They are pronounced the same.
One child: the child's toys
two children: the children's toys
(because the plural noun does not end in "s")
Mrs Smith's car (one person)
The Smiths' car (many people)
Mr Jones's car (one person)
The Jones' car (many people)
In the last two examples, it is pronounced with an extra syllable at the end
Originally posted Remembrance Day, Friday, 11.11.11