Four years ago, I had a month's holiday in the United States, says the physics teacher at Holy Rood High in Edinburgh. I started in San Francisco and finished in Seattle and on the way I went trekking around Yosemite and Mount Rainier.
Then I headed to the Grand Canyon and decided to climb down to the bottom. Carrying as little as possible, just water and snacks, I got there by late afternoon. It was like an oven 30C at 9pm and I lay down in the river to cool down. I was dry again within five minutes.
I set off again at 4am and watched the beautiful colours of the canyon. By 10am I had reached the peak. I was covered in dust but elated from the experience, and I headed off to a hotel to get a drink.
I remember thinking I was glad no one knew me, as I had nothing to change into. But at the desk, I saw someone who looked like an ex-pupil. I looked again, and again, and there were three ex-pupils. They were on a gap year. We spent the day playing hacky sacks, a game where you kick a bean bag around. It was a good day. I hadn't taught any of them, but I knew them through a school trip to Tanzania. They were among the nicest kids of all the ones I could have bumped into.