A new feature has been introduced to Google Calendar which could potentially make it easy for academic staff to manage their contact time with students.
The appointments slots feature lets you allocate a block of time for student contact then divide this into a series of 'slots' of however many minutes you choose. Students can then select one of the slots to make an appointment.
This makes it easy for students to arrange time with their tutor and for staff to schedule in predefined times for studnet contact.
For more information about appointment slots see the link below:
Google Article on Appointment Slots