Each grade level has an emphasis on commas, letter openings, and closings within the Elementary Common Core Language Standards. I LOVE to teach this through picture books. I like to read one aloud and point out when and where the author used different types of punctuation and capitalization. You can even grab several different copies and let students explore the books and add sticky notes when they notice certain features. This makes it fun and enjoyable (plus kids get to read a great story!) My favorite is Drew DeWalt’s The Day the Crayons Quit. Check out this Amazon Listmania for even more great ideas. Have fun with it!