Chief minister Mamata Banerjee turned school principal today and roundly rebuked her 'students' who happened to be heads of the top private schools of Kolkata -La Martiniere, St Xavier's, St James to name a few. And she laid down the law: Kolkata's private schools cannot charge whatever they like as fees. And no donations either. A self-regulatory panel is being set up with top cops in it. "Five lakh rupees!?" she exclaimed at one point of the meeting, where the heads of 50-odd schools had gathered. "How is that even possible?"