Singular vs plural nouns

For the plural form of most nouns, add s.

• bottle – bottles
• cup – cups
• pencil – pencils
• desk – desks
• sticker – stickers
• window – windows

For nouns that end in ch, x, s, or s sounds, add es.

• box – boxes
• watch – watches
• moss – mosses
• bus – buses

For nouns ending in f or fe, change f to v and add es.

• wolf – wolves
• wife – wives
• leaf – leaves
• life – lives
• 
  

Check out more on this website.

http://firstschoolyears.com/literacy/word/other/plurals/resources/rules.htm