Former students, dressed in the school uniform, also took to the stage to speak about the importance of education and the three pillars of Thai society – nation, religion and monarchy.
They also handed out wristbands and hats in the school’s colours – pink and blue.
Many netizens, however, posted messages on Facebook slamming the ceremony saying it was just cosplay.
“I finally understand what the ‘Bad Student’ group mean when they call them dinosaurs,” one netizen said, adding that he was relieved that former student Somsak Jeamteerasakul did not participate in the ceremony.
Somsak is a loud critic of Thailand’s monarchy and its lèse majesté law.