Onion Math

Onion Math (洋葱数学) is a K-12 online science tutoring platform founded in late 2013 by Yang Linfeng, who serves as co-founder and CEO . The company positioned itself not merely as content or a tool, but as an "unmanned K-12 science tutoring" service—using animated short videos and AI-powered personalized learning to create a complete self-study loop without live instructors .

The platform built its user base primarily through word-of-mouth growth, reaching 10 million users with customer acquisition costs well below industry averages, according to FreeS Fund . Its courses covered middle school math, physics, and expanded into high school and elementary grades, with each video running 5-8 minutes and designed to hook students within the first minute . Commercially, Onion Math launched paid offerings in 2016, pricing its "Gold Medal Score Improvement" courses at roughly 40 yuan per month, targeting mass-market affordability with near-zero marginal costs at scale .

On the funding side, FreeS Fund (峰瑞资本) invested across all four rounds from Series A through D, with Legend Capital (君联资本) and Tencent joining the 120 million yuan Series C in February 2018 . By April 2019, the company had raised over 600 million yuan cumulatively from investors including春华资本, Kunlun Wanwei, StarVC, and others . FreeS Fund partner Li Feng noted that the founders' prior experience running a rural education NGO, "Sunshine Bookhouse," informed their approach to balancing educational mission with commercial sustainability .