Craning your neck to see the clock behind you, you were aware of the scraping noise the sweater was making on the chair, drawing eyes from everyone sitting around you. There were five minutes left till the end of class, people signed to each other. Five minutes until there was freedom to eat lunch. A minute, 30 seconds, and finally you’re out. Everyone in Tesla Stem has biological clock wired into their brains, knowing exactly when it’s time to leave, because there are no physical bells to signal the end of class.