In 1883 or 1884, at the age of 13, Montessori entered a secondary, technical school, Regia Scuola Tecnica Michelangelo Buonarroti, where she studied Italian, arithmetic, algebra, geometry, accounting, history, geography, and sciences.
Tahun 1883 atau 1884, saat berusia 13 tahun, Montessori melanjutkan pendidikan ke sekolah menengah teknik Regia Scuola Tecnica Michelangelo Buonarroti, tempat ia mempelajari bahasa Italia, aritmetika, aljabar, geometri, akuntansi, sejarah, geografi, dan ilmu alam.