They're at it again: explaining stuff. What You Need to Know is a fun and informative video site that teaches, well...stuff you need to know. In this installment, they explain the idea of Separation of Church and State. You need to know this, so watch the video. There will be a pop quiz after the show. 

Yes, I know it's not really a pop quiz if you know about it ahead of time. It's still a pop quiz. Watch.