Classes at Tesla’s high school in Karlovac were held in German. He attended the Higher Real Gymnasium in Rakovac, near Karlovac, from 1870 until his graduation in 1873.
The language reflected the school system of the Austrian-controlled Military Frontier, where German had a major administrative and educational role. Tesla’s schooling was strongly oriented toward mathematics, science, and technical subjects rather than the classical curriculum of a traditional gymnasium.
The answer is sometimes confused with Latin because Latin was important in many nineteenth-century European schools, or with Croatian and Hungarian because those languages were also present in the region. For this particular institution, however, the standard biographical account specifically identifies German as the classroom language.
The school also shaped Tesla intellectually. His physics lessons, especially demonstrations associated with teacher Martin Sekulić, helped turn a gifted student’s curiosity into a lasting interest in electricity.