Simplify the following text for a Grade 9 native English-speaking person.
Original: In 1895 , aged 15 , he completed the Nakhichevan school and from 1897 to 1904 studied at the Moscow School of Arts , including in the workshops of Valentin Serov and Konstantin Korovin .
Simplified: In 1895 , he was 15 , he finished the Nakhichevan school and from 1897 to 1904 learned at the Moscow School of Arts , also in the workshops of Valentin Serov and Konstantin Korovin .