Mossotti attended primary school in Monza and secondary school in Novara, apparently showing from a very early age a preference and an aptitude for science, obtaining nonetheless very good results in humanities. The reports of his secondary school to the University of Pavia recommended him saying that he had been a very brilliant student and gained distinction especially in Italian literature, history and mathematics. He also studied logics, philosophy and drawing.
The educational methods of secondary schools around the beginning of the 19th century in the Kingdom of Sardinia were very much based on religion and prayer. The gymnasiums (early secondary schools) were divided into six classes, which among the others included grammar, humanities and rhetorics. Apart from the ordinary teachers, every gymnasium had a prefect, who was often changed, and whose duty was to enforce discipline among teachers and scholars, and to be a spiritual director. About a third of the daily time was spent praying or learning catechism. The school lasted three and a half hours in the morning and two and a half hours in the afternoon. Thursday was a complete day off. The scholars of the gymnasiums were not allowed to read any books which had not been either given or furnished by the prefect. They were forbidden to swim, to go to theatres, balls, cafès or casinos. They could not take part in private plays, and it was the police's duty to see these prohibitions attended to.