Like just about everyone these days, I carry a digital device in my pocket at all times. At the office, I have a powerful desktop, and in the evening, I curl up with my iPad. Each of these contains the knowledge and wisdom of the ages. Kids and parents have as much access as I do.

The ubiquity of knowledge due to digital devices has led many educational theorists and practitioners to wonder whether teachers are even necessary anymore. Can't everyone just look things up, do calculations, and generally provide themselves with just-in-time wisdom-on-the-spot?

Unfortunately, the truth is that digital devices are not yet transforming education. But what they are doing is putting the last nail in the coffin of the teacher as walking encyclopedia.

In the old days, a teacher could contribute a lot just by knowing more than the students. Teaching was composed of content knowledge (what the teacher knows and can transmit) and pedagogy (how the teacher manages classrooms, motivates students, makes complex ideas clear, and teaches learning-to-learn skills). Content knowledge is still crucial, but a "walking encyclopedia" is of declining value when everyone can find out everything all the time.

Does the decline of the walking encyclopedia diminish the role of the teacher? Just the opposite. When kids are immersed in too much information, what they need is a guide to help them learn how to comprehend complex texts and understand and organize information. They need to know how to write, how to solve complex problems, how to set up and carry out experiments, how to work well with others, how to contextualize their own thoughts to reason productively, how to manage their own behavior, how to maintain positive motivation, and how to be productive even in the face of difficulties. Each of these objectives, and many more, are at the heart of effective pedagogy. All are aided by content knowledge, of course, but a teacher who knows a lot about his or her discipline but not much about managing and motivating students is not going to succeed in today's world.

It is my experience that the teaching innovations most likely to enhance student learning are hardly ever those that provide new, improved textbooks or digital content. Instead, they almost invariably provide extensive professional development to teachers, followed up by in-school coaching. In each case, the professional development and coaching focuses on pedagogy, not content. We've found the same pattern in all subjects and grade levels.

The task ahead of us in evidence-based education, I believe, is to use evidence of what works in pedagogy to help teachers grow as motivating, engaging, self-aware learning guides, capable of using general and subject-specific pedagogies effectively to help students become eager and capable learners. My encyclopedia walks with me in my pocket wherever I go. That's true of students, too. They don't need another at the front of their class. What they do need is someone who can make them care about, comprehend, organize, synthesize, and communicate the megabytes of information they carry.