I was teaching an ex-g/f to drive a few years back.
She was learning clutch control this day. And she was doing really well with it too.
Then out the blue she says "If its in first gear but i wanna go backwards whats gonna happen? Will it break the gearbox?"
Err, i had to explain that the car doesnt know, or care, whats shes thinking. It'll go forward if its in 1st!
In fairness she did go very red when the penny dropped