Here’s a great video tutorial (~45 min) on how to train long-term memory for your kids (and you) using the pegging system:
http://www.youtube.com/watch?v=kWoM9aHK6Kk
Wiki article: http://en.wikipedia.org/wiki/Mnemonic_peg_system
Excerpt:
“A Peg system is a technique for memorizing lists. It works by pre-memorizing a list of words that are easy to associate with the numbers they represent (1 to 10, 1-100, 1-1000, etc.). Those objects form the “pegs” of the system. Then in the future, to rapidly memorize a list of arbitrary objects, each one is associated with the appropriate peg. Generally, a peglist only has to be memorized one time, and can then be used over and over every time a list of items needs to be memorized.”
And there are varieties of this method (linked in the Wiki). It will help your kids (and you) obtain Encyclopedic Knowledge.