The new term is already in full swing and it feels as if I've never been away. Our room, painted during the summer, has been returned to its former glory: the photographs I've taken over the years of pupils have been lovingly returned to the walls, and my desk - albeit a little tidier - is in the same place. My new class has settled in nicely and everyone is getting along with only the odd scuffle for the new scissors. So all is going well. I should be on top of the world. But I'm not.
I can't get a particular pupil out of my mind. She isn't in my class anymore, she's now in the year above, so, politically, she's not my problem. But you see, she is, because I'm an adult and she's just a child, and to be perfectly honest I feel partly to blame.
I taught Shelly for all of last year. She was "chubby" when she started the school at five, but it soon became painfully obvious that her weight was giving her problems. She couldn't run with the other children and inevitably ended up in tears if no one wanted to play with her. We discussed bullying and the damage it makes to a person's self-esteem, we talked about how everybody is different and a person shouldn't be judged because of the colour of their skin or how fat or skinny they are.
I felt we were making progress and, towards the end of the year, I prided myself with the knowledge that they were growing up to be well-rounded individuals.
On my first day of playground duty this term, I noticed a gaggle of girls huddled by the loos. There in the middle of them was Shelly, as svelte and willowy as a colt. To a stranger, she would have looked like your average ever-so-slightly scrawny kid, but to me she looked emaciated. You see I've been on more diets than a dietician has heard of. I've done the cabbage soup and lost 6lb, then piled them back on doing the "just a shake for breakfast, a shake for lunch and a low-calorie meal in the evenings". And, as a professional dieter, I know that there is no diet on the planet that can make a 10-year-old girl shed well over three stone in six weeks.
The following day I cornered her, asked if everything was all right and said that if she ever wanted to "just talk", my door was always open. She smiled and ran off to play with the others, all now competing to be her "new best friend".
The staffroom is full of it. "Doesn't she look well?" "Isn't it great that she's finally losing all that puppy fat?" I had to walk out. Hasn't anyone figured out that it is nigh on impossible for her to lose that much weight over the holidays - unless she's starved herself for most of the six weeks? And even if she's just been on a diet, it must have been one hell of a strict regime to lose that amount.
She's just 10 for Christ's sake! At 10 she should be allowed a bit of puppy fat and should be encouraged to eat the odd cake without the fear of it sticking to her hips. It's what you do when you're 10.
Perhaps if I'd skipped the bit about the importance of healthy eating from my lesson-plan, things may have been different; or hidden the dieter's milkshake in my drawer. I could have demanded that all parents divert their children's attention away from the media for fear that the words "Atkins", "diet" and "Hollywood star" should appear in the same sentence. I could have, but I didn't.
Shelly's been taken out of school now. Just a few weeks in and already she's had to miss lessons. Funny how when everyone was worried about her weight, she never missed a day.
Jane Thompson teaches in a London primary. She writes under a pseudonym