Question: what is the difference between putting the apostrophe before or after the s?
Answer: Generally, if the noun is singular, the apostrophe goes before the s. The witch's broom. If the noun is plural, the apostrophe goes after the s: The witches' brooms. However, if the word is pluralized without an s, the apostrophe comes before the s: He entered the men's room with an armload of children's clothing.