On this entirely voluntary occasion, some departments had 100 per cent staff participation. I could confidently claim to be surrounded by good teachers.
The following day's Daily Record carried the stark headline, "I'll boot the bad teachers, says Liddell." Quite apart from the fact that the article revealed that the Education Minister did not say this at all, it exemplified the abiding appeal of teacher-bashing to screaming tabloid editors. Education authorities and schools have responded valiantly to this deluge of criticism by highlighting success stories from state schools. These are not difficult to find except when prejudice impairs the vision.
The so-called quality press also enjoys playing to populist prejudice by regular vilification of public-sector education. Andrew Neil set the tone on his arrival at North Bridge with an article about the "culture of mediocrity" in Scotland's state schools. The Scotsman Publications group has deferentially taken up his cue, with frequent bouts of anti-teacher bile billowing from its organs. Intriguingly, in an apparent fit of public contrition, The Scotsman has now embarked on a weekly education supplement. Headlines such as "Top marks for teachers" referring to an ICM poll of parents must surely have Mr Neil choking on his caviar.
Being a cultural nomad from the west, I still read the Herald, which has always maintained a more objective stance on educational matters. It does, however, share The Scotsman's fawning admiration for the independent sector, with three photographs in one recent week celebrating the glories of private education.
Blatant adverts for independent schools frequently masquerade as articles, and these sometimes appear as overtures to "special advertisement features" when the newspaper's loyalty is repaid with a few bobs' worth of advertising - a neat deal for all concerned.
There are of course some prominent examples of really bad teachers, who have a disproportionate effect on the public perception of the profession. They are far fewer than in the much-glorified past, and the impotence of education authorities and schools in getting rid of them is ammunition to detractors. I noticed on the blackboard in a biology class a definition which seemed to fit the lazy and defective teacher perfectly. "Parasites," it said, "are creatures which obtain their food from the living body and often damage or poison it."
There are a few wasters and chancers who, after years of indolence, gain accelerated access to the ultimate lottery scratch-card - the application form for early retirement. Over the years I have watched several go off to hold court as education experts in the golf clubs of the land, while those who soldier on strive to compensate for their galloping ineptitude. Some of these retirements are granted on grounds of ill-health to characters who are about as sick as Desperate Dan.
To the politicians, to the press, to the many incarnations of Joe Public, who despise teachers because they suffered at their hands, and purport thereby to know all about schools, I would say, "Come and see a school at work. Have a walk around Holy Rood or almost any school, unannounced, any day of the week. You will encounter hard-working committed people doing their professional best to meet the needs of the children in their care."
There are no more bad teachers than bad dentists, bad nurses or bad taxidermists. It is simply that it is much easier to tell a bad taxidermist to get stuffed.
Patrick Sweeney is headteacher of Holy Rood High School, Edinburgh