I think that depending on each situation, both things can happen.
It would be:
Green-Windy
Red-Sky
Blue-Twi
Vio-Time
Perhaps the first lesson could go individual, and then they could have a group session c:
It would be:
Green-Windy
Red-Sky
Blue-Twi
Vio-Time
Perhaps the first lesson could go individual, and then they could have a group session c:
That's a great match-up with the "students" and "teachers" ! 
And to have them do individual lessons and then a group session is a great Idea!
And to have them do individual lessons and then a group session is a great Idea!