Complex sentence: In 1933, she joined the Vic-Wells Ballet School, the predecessor of today's Royal Ballet School, training under the direction of Ninette de Valois and such teachers as Olga Preobrajenska and Mathilde Kschessinska.
Split into simpler sentences: In 1933, she joined the Vic-Wells Ballet School, the predecessor of today's Royal Ballet School. She trained under the direction of Ninette de Valois and teachers including Olga Preobrajenska and Mathilde Kschessinska.