Teachers, coaches, docents, group leaders: Take attendance without calling out name after name! Having your participants (students, etc.) "check in" using their location-aware phones!
How? Make an account at https://youhere.org, and create a class. Set an GPS fence, or "inclusion zone" for your meeting (classroom, etc.)
Your students: Each installs this app on their phone. Thereafter, they use the app to 'check in' to your class.
The app uses the phone's location capabilities to see if they're in the right place at the right time (according to your attendance requirements). Results are logged to your Youhere.org account for easy record keeping.