There are a number of online games that have been designed to teach punctuation and capitalization skills. A number of these games can be found at the somewhat ironically named "4you4free" language arts games website. These free games include "Dan's Edit Machine" and "The Common Comma," and make learning these basic rules of English grammar fun and engaging.
Instruct your students to print out a page of YouTube comments, and a comments section of similar length from a New York Times online article. Have the students use a red pen to circle all of the incorrect uses of punctuation and capitalization in each comments section. Have each student share their results with the rest of the class, and ask them to reveal which site had the most mistakes in the comments section. Lead the class in a discussion of which site's users sound the most intelligent, and guide the conversation to show that people who use improper grammar are perceived as lazy or uneducated.
Have the students watch a short news segment, and ask them to create a transcript of the dialogue in the video. Compare what they write down to your master transcript of the tape, taking care to note if your students have properly capitalized proper nouns, such as titles, names of people, place names, and days of the week. The correct punctuation for possessive nouns and the use of quotation marks can also be tested using this exercise. This will also improve their listening and comprehension skills. Make sure to show the video multiple times so that the students have time to transcribe the whole segment, or have each student use a laptop and headphones so that they can work at their own speed.
Return each student's most recent report or term paper, and note their ongoing mistakes regarding punctuation or capitalization. Ask each student to go online and create their own personalized study guide or reference sheet by copying down relevant maxims from reputable online sources, such as Purdue's OWL.
Listen to the rap song "Dots and Dashes." Using this song as an inspirational jumping off point, have your students make their own song. You can assign each student a "verse" of the rap, with each student composing two to four lines about a certain rule or article of punctuation to share with the class. Film the class where the students perform their raps, and place the video on YouTube for future classes to watch.