It’s true that there’s no such thing as a dumb question when it comes to the Concept/Question Board (or KWL chart). It’s okay for students for students to put up whatever unit related questions they have whether they’re silly or not. However, what’s not okay is for those silly questions to stay up on the board without answers throughout the unit.

Your teaching should be based on the questions that students have about the unit and should address their misconceptions. If they’re learning and retaining that information then they should be able to answer those questions and move them to the concept side or they should be able to to the Learned column on a KWL chart. Otherwise you’re reinforcing incorrect information rather than disproving it.