When I was young, I believed that IQ was a "fixed" thing. You take a test & that's your score. That's apparently a common notion.

Not necessarily so.

Your brain is part of a living organism. stimulating it strengthens its function. You can do crossword puzzles, play trivia games, etc. Researchers at the University of Zurich found that one activity can raise your IQ by nearly ten points.

Learn to play a musical instrument.