You can more precisely set the center of your geofence by walking around your class with your own phone. Here's how:

Setup

1. Install the Youhere app on your phone and join the class:
   .
2. After joining, identify yourself as the class owner:
3. Click this button to initialize this location process: Initialize

On location

1. Physically go to the needed location with your phone.
2. Bring up the Youhere app and start moving around your location. Moving in a path along the extremes is best.
3. As you move, tap "Check me in" on the app at about 10 different locations.
4. Ignore any messages the app tells you about being 'here' or not, etc.
5. Just keep moving and tapping to check in.

Finish up
Come back to this window and click the "Set from location" button.

You got it! That's how you set up a check-in event.

If you want to proceed, you'll need to make an account, so your check-in information, and app check-ins from your participants can be saved.