Simplify the following text for a Grade 11 native English-speaking person.
Original: Between 1936 and 1939 , she studied organ privately with the famous organist Marcel DuprÃ , and in 1939 she joined his organ class at the Conservatory .
Simplified: Between 1936 and 1939 , she studied organ privately with Marcel DuprÃ , whose organ class at the Conservatoire she joined in 1939 .