He is born of demon family. So all those class friends, they were also sons of demons. So there is no question of Kṛṣṇa consciousness. But he learned Kṛṣṇa consciousness from the womb of his mother.
So he was trying to preach. Because he was king's son, there was no other opportunity for preaching, and he was a five-years-old boy. He took the opportunity in the classroom, as soon as the teacher is away, he would preach. He would preach. This is preaching spirit. As soon as you get some opportunity, preach. What is that preach? Preaching, Caitanya Mahāprabhu has advised us, yāre dekha tāre kaha kṛṣṇa-upadeśa (CC Madhya 7.128). This is preaching. "Whoever you meet, simply speak of the instruction of Kṛṣṇa." So if you are advanced, if you know what is the instruction of Kṛṣṇa by reading Bhagavad-gītā, you can preach to others.