Sounds to me like they provide an API for "5-minute SIS Integration for Educational Applications" (from their home page) and that an SIS is an "information system [that] capture[s] and store[s] data on students — from class lists and attendance to grades" (from the TC article).
One of the major pains in the butt for a teacher is getting students set up on a learning web app. Either you spend a bunch of your own time making an account for each student (which is time you could spend doing something more important) or you spend a bunch of class time having students sign up for the accounts during your teaching period (which is time you and they could spend doing something more important).
If a web app had a secure API to include all of my class lists automatically, I'd be much more likely to use it.
Yeah I guess their target audience would know what those things are. That's why I hedged my comment. I'm glad they're doing well, obviously doesn't seem to be a problem for them.
They provided a "vertical network" for K-12 Education data (your kids' test and homework scores), similar to what companies like Ariba and CommerceOne provided for manufacturers and what Facebook and Twitter provide for Advertisers.
