Richard Rudolf Klein (b. 21 May 1921 in Nussdorf / d. 17 December 2011 ) was a German musician , composer and university lecturer. The great variety of his compositions cross different genres such as children's music (often in the Orff Schulwerk style), hymns, stage and orchestral music, chamber and instrumental concertos and chamber music. In 1948, Klein became one of the youngest to teach music theory at the Musikhochschule Stuttgart. The following year, he became professor of music theory at the Northwest German Music Academy in Detmold. In the period from 1960 to 1984, he taught composition at the Musikhochschule Frankfurt, and from 1985 to 1996, Klein taught at Dr. Hoch's Conservatory in Frankfurt. Over a period of four decades, Klein was a music lecturer/recording artist of the publisher Fidula.