"Close your eyes and put your heads down," I told my class. "You are going to travel back 100 years in time. You are a soldier in the trenches. Your feet have become so wet with mud that you can no longer feel them. You haven't slept properly in days. When you do sleep, you are woken by rats. You can see dead bodies lying in no-man's-land and you could be ordered to go over the top at any moment."
There was a loud knock on the door. Our time travel skidded to a halt as the secretary entered, brandishing a lunch box.
"Rebecca's mum just brought this in. Is all the dinner money in the basket?" Back in the current millennium, children stampeded to extract envelopes from bags.
"Close your eyes again," I ordered, when the whole class was seated. "I'm going to read the next few pages and I want you to imagine how you would have felt in that position."
We had been reading War Game, Michael Foreman's brilliant book about four young soldiers in the First World War. We had just reached the final, and most dramatic, section.
I started to read. All heads were down, all eyes closed, as the children put themselves in the place of a Tommy in the trenches.
There was another knock. "Please can we have Dexter and Madison for their music lesson?" I nodded as the two soldiers fetched their guitars from the corner, managing to knock over a pile of books in the process.
Then I carried on reading. The atmosphere was tense. The Christmas Day truce was over and the soldiers were about to go into battle. We stopped to pull out adjectives from the text.
"How would you feel if you were there?" I asked. A forest of hands appeared, competing to offer the best synonyms for "scared".
"Why did they carry on, Miss?" asked Chelsea. "They made friends in the football match. Why didn't they just tell the man in charge that they didn't want to kill them?"
"Why do you think they didn't?" I asked, as the door opened to admit three six-year-olds holding science books. The next few minutes were spent in admiration of drawings of worms and ladybirds. As they left, I glanced at the clock - there wasn't time for philosophical discussions about the ethics of war. I pressed on.
"Look at these sentences," I said. "How does the writer make you feel as though you were there?"
The door swung open. Two Year 6 children stood clutching a poster.
"Can we tell everyone about our cake sale on Friday?" they asked. I gave them exactly 37 seconds.
"Let's finish reading the book," I said. We read on. The main characters had just gone over the top when the fire alarm went off. As we filed back into the classroom 10 minutes later, I realised we had exactly 17 minutes of the lesson left.
"Can we finish the book now?" asked Ryan. "What happened to them?"
"They all died," I said. "Now write about it."
Jo Brighouse is a primary school teacher in the Midlands