Use the same app whether you are a professor or student. Professors can utilize their smartphones as powerful QR code scanners which enable them to scan a huge number of codes in a matter of minutes and students can use the app as a way to track past attendance, plan their next attendance and read news from professors.
No more doubts on which classes you missed or scratching your head over how many classes you have left to attend - all you need is to open QR Student and check yourself. This makes attendance status transparent for both students and professors.