Yeah - perhaps the person was scared on the ground too !!! Be firm but fair and let her know you are the leader but without being aggressive of course. I find that with horses which are bored in the school you can do lots with poles on the ground. I have them dotted around so that you sometimes trot over a pole as you do a circle or change of rein or come down the inside track and sometimes not.

I kind of try to think of games to play if you like, just to make their life more interesting in the school. I try to think of different ways to change the rein too as you school them so never change the rein the same route more than twice in each schooling session. I find that makes them think a bit more and not switch off.