Every year, more than nine million students in China sit a high-stakes examination - the gaokao.
The latest test took place on Sunday and Monday. It is the only way for students to gain entry to university and pressure is high from parents and the nation.
The gaokao is seen as a make-or-break opportunity, especially for those from poorer families, in a country where a degree is essential for a good job.
The exam is tightly policed, but the pressure means cheating is perhaps inevitable.
The authorities have installed closed-circuit television in examination halls and metal detectors at school entrances to ensure students do not sneak in smartphones.
Beijing school officials banned students from bringing in "computerised watches", reported Sina News, and tracked the delivery of examination scripts to schools by GPS to ensure the questions were not leaked beforehand.
Officials in Henan province went as far as deploying a drone carrying a radio scanner to catch cheats.
The six-propeller drone hovered over two testing centres in Luoyang city, scanning for radio signals, reported Dahe Online.
Officials said any signals found to be concentrated in the buildings would indicate information was being sent to devices smuggled into examination halls. They said they did not detect any unusual activity.