The emotions sometimes created by the words "I don't know" are terrifying. Yet I find them to be tremendously powerful too. To admit that we don't know something gives us a vulnerability that exposes us to others. It means that perhaps we have a weakness or shortcoming. Frankly, I see this as a willingness to admit what I don't know and an openness to learn.
But how does this play out in a classroom? What if the teacher doesn't know the answer? Will that make them look less qualified to teach? Less qualified to guide the learning of students? Less of a teacher? No it doesn't. It means that they are open to learn, open to explore, and open to engage. This is where learning begins. Having the teacher as a mentor and a guide is a very powerful approach. Shifting to this perspective is where students become invested in their own learning. Ownership of learning is in my opinion an essential element to further learning.
This happens through conversations - online and offline. This happens by following an idea to see how it connects to others' ideas. The notion that students need to come to school as empty slates is just not relevant anymore. Even five-year-olds come into Kindergarten with a wealth of knowledge. Teachers have the opportunity to teach students how to make connections. They can show them the relationship between ideas and take them further into analyzing how they relate to each other.
I don't know is powerful. It is an invitation to learn.