HYDERABAD: The contractual teaching staff of Osmania University has decided to express its resentment after the government failed to deliver on their demands despite several assurances, by not attending invigilation during exams. All contractual assistant professors and teachers will also don black badges while the University campus as well as those of its affiliated colleges. OUTA-C and OU-CAP had demanded an increment of their salaries by 75 %, along with regularisation of their jobs and implementation of ‘equal pay for equal work’ norm.