Revisiting Seven

"The Magical Number Seven, Plus or Minus Two" was a famous, influential paper (1956) by cognitive psychologist George A. Miller introducing the idea of cognitive 'chunking' of items.

Related to it, in a post yesterday, Nathan Kraft passed along an interactive number memory test that some may find fun/interesting:
http://www.humanbenchmark.com/tests/number-memory

Give it a try, or like Kraft, you may even find it a useful game to explore in a classroom situation.