Anne had not been paying attention or doing a very good job.
She had been giggling and was just generally being naughty.
Suddenly I heard Lydia say loudly,
"NOOOO.... Get your finger out of your nose! When you are doing school you do not have your finger in your nose. You're just fiddling around with that finger!"
You can pick your friends. You can pick your nose. You just can't pick your nose at school.