From 1972 to 1981 de Vries started to teach theory at the former conservatory of Twente, and he was appointed as a lecturer in theory, instrumentation, and composition at the conservatory of Rotterdam in 1979. Among his many students at this school, today also known as the Rotterdam School, are Thorkell Atlason, Antonio Pinho Vargas, António Chagas Rosa, Oscar van Dillen, Andreas Kunstein, Sergio Luque, César de Oliveira, Juan Felipe Waller, Philemon Mukarno, Astrid Kruisselbrink, Florian Magnus Maier, Felipe Perez Santiago, Joey Roukens, Edward Top, Jian-Hua Zhuang, Evrim Demirel, Gerda Geertens and Rob Zuidam. De Vries gave master classes in Brussels, Paris, Manchester, Porto, Moscow and San Francisco.