Until Tuesday, last week, I felt the only way to change Tony Blair’s mind about the war was to protest. Now I am not so sure. The events of last week in my school have prompted me to challenge those who feel it is right for children to leave school and join the massed ranks of dissent.

On Monday, the day George Bush gave his final ultimatum to Saddam Hussein, I wondered whether anything would come of the promised civil disobedience.

I had heard nothing from my students. In liberal, affluent Cambridge, protests had been limited to a few banner-waving peaceniks.

Yet, come Tuesday morning, there were rumours of a sit-down in the playground. When I spoke to my Year 9 group and let slip that I too felt the war to be wrong, I received applause and realised the weight of anti-war feeling among them. Why had I not seen it coming?

Sure enough, pupils massed in the playground. I joined the assistant principal outside. We tried to tell them that it was good to have an opinion and express it but that sitting in the playground was not the right way. We asked them to write their opinions down, and we would send them to our MP, Anne Campbell, who was to resign as a ministerial aide later that day.

Also, in our hearts we felt the same way about the war, so why protest against us? But two Year 11 pupils ignored us. They led a charge out of the front gates. In seconds the playground almost emptied. How many of them knew what they were doing? How many fully understood the circumstances of this war? I, for one, did not.

We did our best to get on with teaching the few remaining students. We bundled all that was left of Year 9 into one classroom and asked them to write down what they thought. A few drew pictures. Some chatted about football, or television. There was a knock at the door. I went out to see who it was. A Year 11 girl stood there, eyes wide with excitement.

“It’s great,” she said breathlessly. “We’re in town, at the Guildhall.

We’ve come to get more people.” I told her that in no way was I letting under-age children out into town without supervision. That they had put us in a very difficult position. She looked crestfallen. She had not considered this, it seemed.

At break, reports began to come back into school. One boy had climbed over a car. His picture was to adorn the local paper, stood on the roof, arms raised in bizarre celebration, as if the lowly taxi driver who had dared get in his way was somehow linked to Bush and Blair. Another had torn up a Stars and Stripes. This greatly upset one of my colleagues, an American.

“That is our flag, not Bush’s,” she said.

Outside, on the green opposite the school, some children were sitting down.

Others milled around, chatting. Not a banner in sight, not one raised voice. This was clearly not a protest - it was something far more insidious and potentially damaging. I asked some of them why they were here. “Because the war is wrong,” they told me. I asked them why. “Because Saddam has a nuclear bomb,” one said. “It’s just about the oil,” said another. “Because we’ve been told that striking school is a good way to get our voices heard,” said a third.

By now, the Year 11s were getting worried. One girl was in tears. “It’s all my fault,” she said. “I didn’t want it to be like this.” Gradually they drifted back to school. One boy, one of the youngest and smallest in the school, took off his sweatshirt. “This school is scum,” he said. When told that some of us had marched against the war, he quietened down. I wondered who had fed him this propaganda.

On Friday I was called out of lessons and asked to go to the front gate.

Outside were at least 100 protesters. “Come with us!” they urged students, who stood anxiously, wondering what to do. The gates were locked. “Shame on you!’ the protesters catcalled. I wanted to call shame on them - for putting us in such a difficult position.

I remembered the events of Tuesday, when a student with Asperger’s syndrome was found wandering around town on his own. Could these people not see what they were doing? Or that we have a duty to take care of the children we teach?

For me, the final nail in the coffin came at the end of Friday. A group of pupils wanted to get together to work out a way to protest properly. They had realised the ad hoc way they had gone about it on Tuesday had not worked. This time they would get us involved and not assume that, as part of the establishment, we were pro-war.

During afternoon registration I read out a note from them. One of the girls who helped to organise the Tuesday protest asked if anyone would join her at a meeting. No one volunteered, not even two girls who had only the day before taken the day off to show their support.

There are students at my school who know far more about the conflict than I do: who can quote Resolution 1441 word for word, who read the papers and talk to their parents about the pros and cons of war.

But there are others who used it as an excuse to miss lessons, waving their arms and shouting without having a clue why.

And, potentially even more worrying, some seem to be bullying others into thinking the way they do. And what, or who, does this remind us of?

Darren Coxon teaches at Parkside community college, Cambridge