The best title of any education book is Ian Gilbert's Why Do I Need a Teacher When I've got Google?
I was thinking of it this week when interviewing applicants for a teaching post. Like many interviewers, we ask would-be teachers to conduct a lesson that we observe. We also get them to meet a panel of students who give us feedback. And in the interview itself we test candidates' subject knowledge and pedagogy.
We think this is important. Subject knowledge on its own is not enough to guarantee that a teacher will be any good. In fact, often it can be synonymous with their being bad. I suspect we have all been taught by a supposed expert who, as the 18th-century poet Oliver Goldsmith put it, provoked our admiration "that one small head could carry all he knew".
We admired the depth of their knowledge, their capacity to perambulate around the outer edges of their subject and their ability to answer any obscure question. And their lessons have bored us into a state of comatose submission.
As a feckless teenager, I was taught by someone who clearly had a passion for his subject, religious education. Sadly for him, none of us shared it, because of him.
I would always wait until five minutes into every lesson, put my hand up and ask some provocative question, such as: "What is God?" Then, like a child who has just thrown a firecracker over a fence, I'd sit back and watch the teacher assume that we were interested in his labyrinthine responses. We weren't. I look back in self-conscious distaste at the knowing game of "bait the teacher" I was playing.
This week at interview, a candidate told me that she would never talk to a class for more than 10 minutes because the children of "Generation Y" somehow needed to learn everything through ICT.
I was unconvinced. In my experience, young people have so much ready access to information that they take it for granted. So when they do get a teacher who knows a lot but can also explain it in a way that is engaging, impassioned and exudes fascination, they love it.
Young people appreciate great teachers as much as they ever did but are more intolerant of mediocre ones. They know that time spent listening to an educational duffer could be more productively devoted to a search engine.
But brilliant teachers don't just give us information - they give it a context, they share a perspective, they help a world of giddying complexity to make sense.
It's why, as school leaders, we need to keep our focus entirely on the classroom, on developing the next generation of inspiring teachers. Our aim ought to be that a student is heard saying: "Why do I need Google when I've got a teacher?"
Geoff Barton is headteacher of King Edward VI School in Bury St Edmunds, Suffolk.