Open School is a national institution where anyone can take exams without any restrictions. There are no barriers to entry. You can take exams for any type of education through NIOS. Open School conducts exams twice a year, in April-May and September-October. You can apply for either of these exams. Attending school daily is not necessary to take exams through Open School, nor is it necessary to have a attendance of 60% or 80% in school.