Rebecca Black, left, is not related to Cathie Black, right.

Cathie Black is trending on Twitter right now which makes sense, considering the news that the head of the largest school system in America is stepping down after three months. But it also is a touch confusing for people who don't have a clue who Cathie Black is. So let us help. To start, Cathie Black is not Rebecca Black's sister.

Before Mayor Bloomberg announced that she was his pick for Department of Education Schools Chancellor, Cathleen "Cathie" Black was the chairwoman of Hearst Magazines. She had no previous experience in education, and her children were not public school students, which pissed off a lot of people. Eventually, however, she was given a waiver allowing her to take the job anyway. And once in office she almost immediately started making some serious gaffes. Like the time she suggested that the way to solve overcrowding in schools was more birth control.

Things quickly got worse as parents, students and teachers would verbally assault her in public meetings (it didn't help that she appeared to mock them). Her short public career did have one highlight, a successful (and highly scripted) trip to Albany, but it wasn't enough. When it became clear that she was an incredibly unpopular liability on the Department, the writing was on the wall. Earlier today Mayor Bloomberg announced that she would be replaced by Deputy Mayor Dennis Walcott.

But here, let's make this really easy. This is Cathie Black making her birth control quip:

And this is Rebecca Black doing her, uh, thing: