Your grandfather is sitting in the living room working on a crossword puzzle on a Saturday morning. He thinks these word puzzles are fun, but he also does them for another _______. He knows that brain games, like crosswords, help build his “mental muscles.”

The term “mental muscles” describes your brain’s ability to finish _______ tasks. Like the muscles in your body, your brain’s “muscles” need exercise. While your brain works all the time, that work does not necessarily exercise your brain.

_______, sometimes your brain just needs time to relax and play. It is believed that brain games, like crossword puzzles, make your brain work while playing. They build your concentration by making you focus on some skills for a long time. For example, when doing a Sudoku puzzle, you focus on organization. Other games that may improve brain power are jigsaw puzzles, mahjong(麻将)and chess. They can help you to _______ patterns(图案), solve problems and memorize information.

Games build your brain by making you think differently than you normally do. For example, crosswords use clues to help you fill in a grid(方格) with words. A crossword clue might be “a fruit with yellow skin.”. Your answer must fit in the grid. The word for this clue has six boxes. To fill in those boxes, you need to answer the clue with the word “banana.” Other words in the puzzle share some of the same letters. Because of this, answers to previous clues help you find answers to other clues. Crosswords make you remember the words you know and also help you learn new words. _______, filling out crosswords builds vocabulary and memory. When choosing a game, choose something that will improve a skill you are working on. It should challenge you. If it does not, it will not make your brain work hard enough. But a puzzle that is too hard isn’t any fun. So _______ something that is fun for you, and enjoy building your brain.