Did I hear correctly?

I was doing a lesson on electricity with my Year 9 class (Form 2 in old money) and I asked them to complete a worksheet in which they had to write down things that use electricity. Nothing too taxing. The pupils started to ask me how to spell different words so I wrote them on the board - things like video, toaster, fridge. You get the idea. Things were going well until one boy asked, “Sir, how do you spell TV?” Even in a class of bad spellers this caused an uproar.