John Entwistle, who taught at Pershore high school, Pershore, Worcestershire, was found guilty of serious professional incompetence by England's General Teaching Council.
It found that between October 2002 and October 2003 Mr Entwistle failed to assess student work regularly or to provide adequate feedback, and that his classroom management and the way he communicated with pupils was poor. He resigned from the school last year for a job in the youth service.
Mr Entwistle had taught at the mixed high school since 1979, and it was the only teaching post he had held.
There had been concerns about his performance since the mid-1990s, and in 2002 there was a series of complaints from parents.
He was offered a range of support, including guidance from other staff, and after Mr Entwistle made little progress after being given targets to improve in early 2003, he was issued with a written warning. Steven Davies, science inspector for Worcestershire county council, conducted several classroom observations on Mr Entwistle.
He said: "He was a traditional teacher, his subject knowledge was good . .
. his strength was that he would try to relate to children, but I wonder just how successful he was at that.
"I don't think he should have been a teacher. He had been in teaching for too long, and I suspect that some of the problems we were seeing were present around 20 years ago."