Three Mistakes of My Life by Chetan Bhagat

'Leave it. No SMS-ing in my class,' I said.
'It's just...,' she said as she stopped her hand midway.
'I will go if you don't concentrate. I have turned down many students for this
class.'
She was zapped at my firmness. But I am no Mr Nice, and I hate people who
are not focused. Especially those who hate maths.
'Sorry,' she said.
'We only have an hour. Do your fun activities later.' 'I said sorry' She picked up
her pen again and opened the cap in disgust.