Galileo secured a temporary position as a lecturer at the Accademia delle Arti del Disegno in Florence, where he taught perspective and other artistic subjects, further developing his observational and analytical skills.

Galileo was appointed professor of mathematics at the University of Pisa, a position he held for three years. It was during this period that he allegedly conducted his famous experiments on falling bodies, though historical evidence for this is limited. He started questioning Aristotelian physics.

Galileo accepted a more prestigious and better-paid professorship at the University of Padua, a part of the Republic of Venice. This marked a particularly productive period in his career. He taught geometry, mechanics, and astronomy, and conducted research that laid the foundation for his later groundbreaking discoveries.

Galileo left his position at the University of Padua to become the Chief Mathematician and Philosopher to Cosimo II de' Medici, the Grand Duke of Tuscany. This appointment provided him with financial security and freedom to pursue his research without the demands of teaching.