The incident took place at the Mandal Parishad Primary school in Maradapalem area yesterday.
The students, who are brothers, reportedly collapsed after the teacher asked them to take their shirts off and stand in the Sun for nearly three hours.
One of them is a class 5th student and the other a class 4th student, said the Mandal Educational Officer Saibaba, who added that he would submit a report to the district educational officer after inquiry, and no police case has been filed yet.