One day, when the princes were playing a game, they lost their ball in a well. When the rest of the children gave up the ball as being lost, Arjuna stayed behind trying to get it. A stranger came by and extracted the ball for him by making a chain of “sarkanda” (a wild grass). When an astonished Arjuna related the story to Bhishma, Bhishma realised that the stranger was none other than Drona. Bhishma asked Drona to become the Kuru princes’ teacher. Seeking refuge from Panchala, Drona agreed.