How much school did cesar chavez complete?

According to Wikipedia:
In 1942, Chavez quit school in the 7th grade. It would be his final year of formal schooling, because he did not want his mother to have to work in the fields. Chavez dropped out to become a full-time migrant farm worker. In 1946, he joined the United States Navy and served for 2 years. Chavez had hoped that he would learn new skills in the Navy that would help him later when he returned to civilian life. Later, Chavez described his experience in the military as "the two worst years of my life".