Remember that scorching Thursday a few weeks ago? I do. Here’s how it went: My Year 7 French lesson is over. Pupils now know how to ask for “presents for less than 50 francs”. And we can all leave the greenhouse of a classroom. They stand quietly behind their chairs and I dismiss them row by row. But they don’t get far. I go to open the door and give them an “au revoir”, but the door won’t open.

My first thought (and indeed hope) is that one of them has escaped and is holding the door shut on the other side. Wishful thinking - all are present and correct. And the door definitely will not open. Oh dear.

“Listen up, Year 7. We are locked in.” For some strange reason, this seems to excite them. The boys: “It’s all right, Miss. I’m strong, I’ll open it for you”. “Miss, can I kick the door down? It’s already got one hole in it.” “Miss, shall I climb out of the window?” (We are on the first floor.) The girls: “Miss, how much food have we got?” “Miss, are we going to stay here forever?” The bell has gone, the rest of the school are on their way to their next lesson, and a shut classroom door with a noisy group of pupils behind it does not arouse suspicion - why should it? I send the pupils back to their seats. “Who’s got a mobile phone?” I ask. Twenty-five appear. I ring the school office. “Hello, it’s Miss Brown here. I’m in room A27 with a class of Year 7s. The door is locked and we cannot get out. Could you send the caretaker up please.”

We wait - and wait. We are 15 minutes into the next lesson before the premises officer arrives. He duly releases the class, except for me and two pupils (who have dropped something and are picking it up). But when he leaves the classroom he shuts the door behind him. Yes, we’re locked in again. (I discover that the handle is faulty and you can get in from the outside, but not out from the inside.) A couple of minutes’ hammering soon brings him back and we’re free.

Thank heavens for mobile phones.

Sarah Brown is a PGCE student at the University of East Anglia. This incident happened on her second teaching practice