Complex sentence: She began her career as a teacher for Latino communities in Chicago Public Schools, as a teaching assistant for Marquette University's English department, a Mathematics teacher for St. Martin School, then was a reference librarian for the Elmhurst College Library.
Split into simpler sentences: She began her career as a teacher for Latino communities in Chicago Public Schools as a teaching assistant for Marquette University's English department. She taught as a mathematics teacher for St. Martin School then became a reference librarian for the Elmhurst College Library.