"The point of the spacing algorithms is to show you the card as rarely as possible and still keep it in your brain." http://bit.ly/aHFk2a
3:26 AM - 10 Apr 2010
0 replies
0 retweets
1 like
Loading seems to be taking a while.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.