While you are not required to report participation in order to do the Hour of Code with your classroom, we encourage you to register your Hour of Code event here.
Later in January, after the Hour of Code, we will send out an optional survey to all participants that registered their Hour of Code event. In this survey you can report how many of your students participated, what Hour of Code activity you did with your students, and how your event went, etc.
Since we don't require students to log in to use our content, we don't take record of individual participation to ensure what classes did participate or didn't - other than tracking metrics for total participation around the Hour of Code season. We just ask that you and your students have fun learning to Code!