How to notify a teacher an offilen task has been done?

Hello,

I'm working with moodle 2.7.1 I can't find a way to be notified when students (which are teachers learning moodle with their own practice courses) perform an offline task (like add some resources to their practice courses)  I would like something "like a button to be pressed" in the sense that student should just notify me that they have completed their task so I can check it. 

Does anybody had this same problem? If so, how did you solve it?

Thank you, Jose Pedro