The lecture focused on physics, aiming to illustrate how the weightless environment affects buoyancy, the movement of objects and optics.

Students from five cities, including Beijing and the semi-autonomous region of Hong Kong, peppered the astronauts with questions about living conditions in space and were treated to a virtual tour of the station. The event was also open to the public through a livestream.

Wang Yaping, the only woman aboard the station, served as the main instructor, while Ye Guangfu assisted and commander-in-chief Zhai Zhigang worked the camera. Wang had taught a similar lesson while aboard one of China's earlier experimental stations in 2013.

The three arrived at the station in October for a six-month stay, charged mainly with preparing the main Tianhe module for the arrival of two additional modules named Mengtian and Wentian ahead of completion by the end of next year.

Wang last month became the first Chinese woman to conduct a spacewalk when she and Zhai spent six hours outside the module to install equipment and carry out tests alongside the station's robotic service arm.

Their Shenzhou-13 mission is China's longest since it first put a human in space in 2003, becoming only the third country to do so after Russia and the U.S.