Why Lesson Planet?
In an exercise from the Purdue Online Writing Lab, learners can review 11 rules for comma usage. They then either label 21 sample sentences C for correct as is, or they identify which rule of comma usage is being broken. Though the exercise is available online, and contains a link to an explanation of the rules, it cannot be filled out on the website, nor does the site provide feedback. An answer key immediately follows the exercise.