I used a variant of this game when I taught English in Sweden for a short while. It worked well with younger children. Everybody would stand up. One would start counting upwards from 1. Any number that contained a 7 or was a multiple of 7 would be replaced by "toothbrush" (a good pronunciation test). Anyone who got it wrong had to sit down and was out of the game. It usually went quite well initially as they got the hang of it, but problems emerged in the 70s because they tended to lose count (and I had to be very careful!). Past 84 they were in virgin territory.