Not everyone who talks has thought and not everyone who is quiet is disengaged and not participating. Some students are internal processors in that they think through the questions, answers, and issues as it relates to them without saying a word. Usually when they speak, it can be pretty profound and especially helpful. Often they don't speak up because even as there are internal processors, there are also external processors. Many cannot think through ideas unless their mouth s are moving and they are expressing themselves verbally. They tend to ramble and even contradict themselves in mid-speech. They fight for words and eventually get there, but not without taking up the time and space of the discussion. Both are present in classrooms, and we need to learn to engaged them both. For the external processors we affirm and confirm their discussion by summarizing and paraphrasing their words. They tend to appreciate it. Internal processors often tend to wait to speak up, to think again, and in the meantime someone else may chime in and even change the subject. As you discuss, be mindful that both kinds of learners are present, thinking and learning, even if some are not speaking.