easier level for children

[Timothy D. Prime]

My son is six years old.  To my surprise, he has taken a strong interest in 
chess.  He knows all the pieces and how to move them.

I have been trying to setup gnuchess to run at a level more fit for a 
beginner. A similar question was recently asked on the "bug" list.  I have 
tried some of the suggestions including "book off" and "depth 0" or "depth 1".

So far, I am not happy with the results.  It's just too strong.  Are there any 
other options I can try that will cripple the AI?