Many years ago, I played Scrabble competitively. One of the first things a beginner tournament player should do is learn the two-letter word list. Recently, I created a worksheet that tests your knowledge of all the valid two-letter words accepted in official tournament play in North America. The worksheet makes extensive use of the StringTools package which has terrific tools for manipulating words.
The worksheet link is below if you'd like to try it out, and I'll be happy to get some feedback about it.
If you're an experienced Scrabble player, then you probably already know the entire two-letter word list. I'm currently working on a couple of other worksheets meant for more advanced players and hope to post those in the near future.