Well DS phoned me in a panic after biology - when I took the call, I thought it was that biology hadn't gone OK, but no, he couldn't find his wallet. He definitely had it this morning on the bus as it has his oyster card in it, and says he always carefully puts it into his bag before going into an exam, but it was not in his bag, and he searched and seached, and went all over the school, to every room he had been in, to see if it could have dropped there.
So instead of discussing biology, it was more about calming him down and pointing out to him that we can get another oyster card, and the little bit of money he had on him really didn't matter, and we can cancel his debit card, and it is not the end of the world.
Luckily this all blew up after biology, which after he had walked home and calmed down he said was fine. The wallet might still be in the school, but I guess it is possible it fell out in the bus, or somebody took it, so we cancelled the debit card.
The one thing I was able to tell him was that it had happened to me this morning as well - except that I was actually pickpocketted. I know that because I was waiting at a bus stop, and when I went to get on the bus, my shoulder bag was unzipped and my purse was gone. And within five minutes I had a text on my phone from my bank asking whether a contactless transaction was mine! So I had just spent the morning (after posting about English), cancelling all my cards! Luckily they picked it up so quickly, only the second contactless transaction, and none of the others had been touched. There was about £25 in my purse, but I guess it could have been worse. So having just recovered from that, here we were phoning banks again!