Google Attendance Taker is a free extension that provides you with a way to create a txt file with each student's name and a list of the students who are scheduled to attend a meeting or class. You can also use this to create a txt file of students who have arrived, left, or if a class or event will be canceled.

The tool also provides you with a way to track and manage your attendees, which will give you the ability to mark attendance by clicking on the "on" link on the popup. The attendance will be taken every minute for the students who are scheduled to attend.