The sign-in sheet for the room you're in.

Open a meeting, put the code where people can see it, and email yourself the list when the session ends.

1. 01

   Meetings

   Show a QR code. People scan it and join the queue in the order they arrive.

2. 02

   Rosters

   For a class, email each person a code so nobody can sign in under someone else's name.

3. 03

   Promotions

   Put a discount on the projector. Each phone that scans gets its own code.