Complex sentence: In 1948 he began teaching, and in 1951 he led classes in conducting at the Academy of Music in Poznań and in 1955 became a professor at the National Academy of Music in Warsaw and from 1958 was Head of the Department of Conducting.
Split into simpler sentences: In 1948 he began teaching, and in 1951 he led classes in conducting at the Academy of Music in Poznań. In 1955 he became a professor at the National Academy of Music in Warsaw and from 1958 was Head of the Department of Conducting.