Using Timelines-Present Perfect Continuous-Present Perfect

In my advanced conversation class, a chapter in Touchstone Level 3 has a section about the present perfect continuous and the present perfect.  It's actually pretty complicated grammar and not something that students can understand that easily.

For example, what is the difference between these two sentences?

1. "I've been watching Survivor since I was in university." (present perfect continuous)

2. "I've watched survivor since university." (present perfect)

Both are talking about repeated activities that happen mostly in the past, but what is the difference?  It's subtle.  In the first case, it's an activity that began in the past, but is still happening now.  In the second case, it's an activity that began in the past, but it's a bit ambiguous whether or not the activity is happening in the present.

To explain this to students, timelines can be really helpful. 

 Present Perfect Continuous

Past-----Present-----Future

Yes-------Yes--------??

Present Perfect

Past----Present----Future

Yes------??---------??