Public reflection type:

Public apology karaoke:

Weird Allan Kaprow presents: Public Apology (Karaoke)

http://zacharygough.ca/new-blog-2/2015/3/5/public-apology-karaoke

I also encountered this artwork called blind field shuffle which i would put in this category.

Prompting others to act type:

The art and social practices workbook:

https://guestwork.org/The-Art-and-Social-Practice-Workbook

http://a.nnotate.com/docs/2014-05-12/bcizgvh6/RP_1_WKBK_FINAL_REV.pdf

Environmental activist type:

Animal watching(?)

https://www.vice.com/en_us/article/payka7/endangered-animal-species-projection-mapped-trees-mexico-city

Not too sure whether this is social practice art cus there is not much social engagement in this art piece.

In general a lot of social practice art is just providing a platform and opportunity or inspiration for others to act and get involved instead of doing the actual artwork themselves.