For Kids
Many websites provide free on-line brain building games, including braincurls.com, which offers a math game that tests your child's shopping IQ. Instead of asking what he or she would buy, it helps the child determine whether he or she could afford it. It also helps children determine tax amounts and costs of items after discounts.
If you are limiting your child's computer time, board games or card games requiring counting, or simpler trivia games are good mind-stimulating alternatives.
For Adults
Word games are a great choice because they are portable and you can work on them whenever you have spare time. If you can't finish now, you can come back later. Word searches and crossword puzzles are popular choices, and come in varying levels of difficulty, from easy to challenging.
Trivia games help stimulate the mind, too. They may pertain to a certain subject or time period. If you select one on an unfamiliar topic, you will use your brain more and might just learn something new.
For Both
If you children see you playing brain builder games, it may encourage them to do the same. Select brain-builder games you can play together.
Many on-line games are not timed and can be played by adults and children alike. For example, some word games require players to think up as many different words as possible from a given set of letters. Both adults and children can take turns guessing words.