When He was just sixteen years old He started His own catuṣpāṭhī (village school conducted by a learned brāhmaṇa). In this school He would simply explain Kṛṣṇa, even in readings of grammar. Śrīla Jīva Gosvāmī, in order to please the Lord, later composed a grammar in Sanskrit, in which all the rules of grammar were explained with examples that used the holy names of the Lord. This grammar is still current. It is known as Hari-nāmāmṛta-vyākaraṇa and is prescribed in the syllabus of schools in Bengal.
During this time a great Kashmir scholar named Keśava Kāśmīrī came to Navadvīpa to hold discussions on the śāstras. The Kashmir paṇḍita was a champion scholar, and he had traveled to all places of learning in India. Finally he came to Navadvīpa to contest the learned paṇḍitas there. The paṇḍitas of Navadvīpa decided to match Nimāi Paṇḍita (Lord Caitanya) with the Kashmir paṇḍita, thinking that if Nimāi Paṇḍita were defeated, they would have another chance to debate with the scholar, for Nimāi Paṇḍita was only a boy. And if the Kashmir paṇḍita were defeated, then they would even be more glorified because people would proclaim that a mere boy of Navadvīpa had defeated a champion scholar who was famous throughout India. It so happened that Nimāi Paṇḍita met Keśava Kāśmīrī while strolling on the banks of the Ganges. The Lord requested him to compose a Sanskrit verse in praise of the Ganges, and the paṇḍita within a short time composed a hundred ślokas, reciting the verses like a storm and showing the strength of his vast learning. Nimāi Paṇḍita at once memorized all the ślokas without an error. He quoted the sixty-fourth śloka and pointed out certain rhetorical and literary irregularities. He particularly questioned the paṇḍita's use of the word bhavānī-bhartuḥ. He pointed out that the use of this word was redundant. Bhavānī means the wife of Śiva, and who else can be her bhartā, or husband? He also pointed out several other discrepancies, and the Kashmir paṇḍita was struck with wonder. He was astonished that a mere student of grammar could point out the literary mistakes of an erudite scholar. Although this matter was ended prior to any public meeting, the news spread like wildfire all over Navadvīpa. But finally Keśava Kāśmīrī was ordered in a dream by Sarasvatī, the goddess of learning, to submit to the Lord, and thus the Kashmir paṇḍita became a follower of the Lord.
The Lord was then married with great pomp and gaiety, and at this time He began to preach the congregational chanting of the holy name of, the Lord at Navadvīpa. Some of the brāhmaṇas became envious of His popularity, and they put many hindrances on His path. They were so jealous that they finally took the matter before the Muslim magistrate at Navadvīpa. Bengal was then governed by Pathans, and the governor of the province was Nawab Hussain Shah. The Muslim magistrate of Navadvīpa took up the complaints of the brāhmaṇas seriously, and at first he warned the followers of Nimāi Paṇḍita not to chant loudly the name of Hari. But Lord Caitanya asked His followers to disobey the orders of the Kazi, and they went on with their saṅkīrtana (chanting) party as usual. The magistrate then sent constables who interrupted a saṅkīrtana and broke some of the mṛdaṅgas (drums). When Nimāi Paṇḍita heard of this incident He organized a party for civil disobedience. He is the pioneer of the civil disobedience movement in India for the right cause. He organized a procession of one hundred thousand men with thousands of mṛdaṅgas and karatālas (hand cymbals), and this procession passed over the roads of Navadvīpa in defiance of the Kazi who had issued the order. Finally the procession reached the house of the Kazi, who went upstairs out of fear of the masses. The great crowds assembled at the Kazi's house displayed a violent temper, but the Lord asked them to be peaceful. At this time the Kazi came down and tried to pacify the Lord by addressing Him as his nephew. He pointed out that Nīlāmbara Cakravartī referred to him as an uncle, and consequently, Śrīmatī Śacīdevī, the mother of Nimāi Paṇḍita, was his sister. He asked the Lord whether his sister's son could be angry at His maternal uncle, and the Lord replied that since the Kazi was His maternal uncle he should receive his nephew well at his home. In this way the issue was mitigated, and the two learned scholars began a long discussion on the Koran and Hindu śāstras. The Lord raised the question of cow-killing, and the Kazi properly answered Him by referring to the Koran. In turn the Kazi also questioned the Lord about cow sacrifice in the Vedas, and the Lord replied that such sacrifice as mentioned in the Vedas is not actually cow-killing. In that sacrifice an old bull or cow was sacrificed for the sake of receiving a fresh younger life by the power of Vedic mantras. But in the Kali-yuga such cow sacrifices are forbidden because there are no qualified brāhmaṇas capable of conducting such a sacrifice. In fact, in Kali-yuga all yajñas (sacrifices) are forbidden because they are useless attempts by foolish men. In Kali-yuga only the saṅkīrtana yajña is recommended for all practical purposes. Speaking in this way, the Lord finally convinced the Kazi, who became the Lord's follower. The Kazi thenceforth declared that no one should hinder the saṅkīrtana movement which was started by the Lord, and the Kazi left this order in his will for the sake of progeny. The Kazi's tomb still exists in the area of Navadvīpa, and Hindu pilgrims go there to show their respects. The Kazi's descendants are residents, and they never objected to saṅkīrtana, even during the Hindu-Muslim riot days.