How is it determined if a question is 'trending'?
I don't know how the actual algorithm works, and, to be honest, I don't think that the engineers would be willing to share that, haha, but I do know the basic idea behind it.
Trending questions are selected based on traffic, i.e. on the number of students who land on a certain question, either from external sources like Google, for example, or from other Socratic pages.
So the higher the traffic on a question in a given period of time, the more likely it is for that question to be trending.
Trending questions change all the time, even if you simply refresh the page, in order to show as many popular questions as possible for every subject available on Socratic.