There are no secret cheat codes, sorry
Check out this link for cheat codes for Reading Express: http://www.cheatcc.com/ds/brainageexpressartsandletterscheatscodes.html
unless you cheat ... no.
cheat codes
bawkbak
you have to cheat
k9lu766
k9lu766
well, one cheat code is HURRIMADURR
jhsduyfgyerfgyry5764yerdg5tgfy56hytyhhju67yth43y67y76j7u665474979237648365784647654657
no
There is a cheat for obtaining the Secret Key. You can use Action Replay Codes for WI-Fi Event Items.