while using a 16-17oyster card, does the person have to touch in and out on the bus?

Question

while using a 16-17 oyster card, and being granted free travel concesion on bus and tram, do you have to touch in and out on the buses?

Answer 1

I think so...
I mean they don't ever over charge you,
so I suppose you're safe,
if that's what you're worried about...

Answer 2

for busses, I think you only have to touch it when you go in only - not on the way out.

on the tube - you need to touch it in and out.