 Giáp's busy political activities took a toll on his postgraduate studies, and he failed to pass the examinations for the Certificate of Administrative Law.Unable therefore to practice as a lawyer, he took a job as a history teacher at the Thăng Long School in Hanoi.As well as teaching in school, Giáp was busy producing and writing articles for "Tiếng Dân" (Voice of the People) founded by Huỳnh Thúc Kháng and many other revolutionary newspapers, while actively participating in various revolutionary movements.