From March 22nd to April 18th, the Social Practice Center of OSA led the activity of "Class at Half Past Four" online voluntary teaching. Every Friday and Saturday evening, Shimmer volunteers conducted voluntary teaching for students of Shangjing and Yujing communities and the youth activity center of Longgang District. Eight live lessons and recorded lessons of six themes were conducted during the project. The live lessons were taught bilingually in Chinese and English and have been watched 268 times. The students were eager in interchange and reflection, often engaging in real-time interaction with volunteers in danmaku. This project has become Shimmer's exploratory yet crucial step towards online free education, for it has transcended through internet the limits of time and space in times of the pandemic.