Old-fashioned classroom question (To Sir With Love)

In the movie To Sir With Love (1967), in the middle of Sidney Portier’s big “new rules” scene, he takes something on a white cord, fairly thin, and throws it in the trash. (In the beginning of the scene he throws a pile of schoolbooks likewise in the trash, so clearly this seems to be another symbol of the “old order”, now useless.) What is it? There seems to be a fair amount of cord - several loops.

I wouldn’t know. This was after my time.

Old-fashioned classroom, sheesh. :smack:

The classroom in question is clearly “old fashioned”, meaning out of date, for the film as well.

ETA - I should have mentioned, it’s also British.