The protesters, led by S Jagadeesh and some leaders of Left parties, claimed that the management had not given any reason while dismissing the child.
A senior management member, who did not wish to be named, claimed that the boy's parents had been creating problems for the school for the last one year.
Police quoted Jagadeesh as saying that the protestors did not want to create problems on the road and that they insisted that the boy be readmitted.
Meanwhile, a group from Parents and Teachers Association told reporters that Jagadeesh was creating problems for other students also, allegedly with support of political parties.
"His motive is something else," they claimed.
On Monday last, parents, some members of Education Protection Committee and CPI MLA M Arumugham, along with party workers, had squatted in front of the office of the District Collector here, seeking 'justice' for the boy.