I know a few people in my class who are going from an acquisition POV - one's comparing children's books, another took transcripts from her younger cousins and is comparing those (like in the exam).
Basically trying to prove a ton of acquisiton theorists. - do some research, I'm sure you'll find a ton of stuff you'll find interesting and want to explore more!
On the other hand, I'm comparing some podcasts with different gendered speakers and comparing male & female group conversation. My friend is actually doing language change; comparing different wedding vows through time
I hope this gave you some ideas and how to get started!
This is my fave part of the course so far, hope you enjoy it too