Google Docs is one of my most used tools, particularly since we are a 1 to 1 school utilizing Chromebooks (and students can turn docs directly into Canvas).
The affordances of Google Docs are many. First, students can work together at the same time on a document. Gone are the days of one student working feverishly while the others in a group watch them. Now students divvy up responsibilities and they tackle their part all at once. A constraint is that it takes the students a little while to figure out how to work on a document at the same time without getting in each others way.