Have you ever told a pupil to "change the record" and they've replied by asking "Miss, what's a record?" Plenty of teachers on the TES online threads have fallen foul of their use of supposedly obsolete language.
As Helena Handbasket says: "Last year, I was talking to a class about a video tape and one kid went, 'Oh, my nan has one of them.' I'm 24. I should not be in a category with a 14-year-old's grandma."
Many confess to "taping" TV programmes, or "dialling" phone numbers, or even to listening to the "wireless".
Carnhot "had to explain that when I was at school the question was not 'What is your mobile number?' but 'Are you on the phone?'"
And Bedingfield recalls the pre-iPod days when youths queued outside phone boxes to ring "Dial-a-Disc" or risk their parents' wrath by using the home phone: "I used to ring and listen when my parents were out as I was afraid that they would say I was wasting money." The fact that it cost 2p to listen to a three-minute song seems like a bargain now.