The game of concentration is a memory matching game that was originally played using a deck of cards. Today, there are many online versions of this memory game.
Instead of a deck of cards, the online versions of the memory game often use an array of themed pictures. The size of the array and the many types and themes available on the web for this memory game are quite varied. Obviously, the larger the array (more cells) the more difficult the game.
Most if not all of these online memory games have timers so that you can keep track of how fast you get.
Listed below are links to the online memory game version of concentration. Check them out and have some fun giving your brain a little exercise.
History, Rules and Strategy
Wikipedia – Concentration (game)
Gamesgnome — 3 x 4 array
Usboomers — 6 x 6 array
Janbrett — 6×6 array
Aplusmath — 4 x 4 array using multiplication facts
Illuminations — 4 x 3 array using numbers, shapes, fractions, or multiplication facts