Became is the past tense of the verb become. When something becomes different, it changes from one state into another. When water froze last night, it became ice. When a caterpillar transformed into a butterfly, it became something entirely new.

People use this word constantly to describe changes over time. Abraham Lincoln became president in 1861. Your grandmother became a citizen after passing her citizenship test. Last summer, you might have become a stronger swimmer after weeks of practice.

The word often appears in stories about transformation and growth. The wooden puppet Pinocchio became a real boy. A shy student might have become more confident after joining the debate team. An empty lot became a community garden when neighbors worked together to plant it.

Notice that became describes a change that already happened, not one that's still occurring. You wouldn't say “I became taller right now.” Instead, you'd say “I became taller over the past year” or “I'm becoming taller.”