Every once in a while, you come across an example of a teacher using a technique in the classroom that captures almost everything you wanted to say about it–Why a teacher would use it. How. 

The topic is building a Culture of Error and this portion deals with how this technique includes but is also broader than establishing psychological safety. 

In a high-performing classroom, a verbalized or unspoken "I don't know" is cause for action. No opt out is a strategy to combat these moments and insist on 'high expectations of student output.