It all starts with the teacher when they are ready to take the attendance. They should generate the QR Code for the given day by selecting a few options like the QR Code validity period and Size of Classroom.
They have two ways in which they can present the QR Code to the class. The fastest way is to display that QR Code on the classroom projector using the public link provided by the app, or more time-consuming way is to ask each individual student to scan that code directly from their phones.
Now Students in the class should scan this code. The app marks the student present only if he/she is within the class radius.