Little Guy asked for a copy of the Greek alphabet yesterday. Andrew pulled out his ancient copy of Philosophical Greek; I printed out a worksheet or two. Little Guy immediately set about figuring out how to write his name in Greek letters. This morning I overheard him calling, "Delta alpha delta!" and spelling out a question to his father.
Every single one of my kids has gone through this phase. It's kind of like codes, y'know? Fun, secret, different. And they learn (painlessly) that English words that have the letters ph and make an f sound (phone, phonics) come from the Greek because of the letter phi, and words where the ch sounds like k (chorus, chrome) come from chi, and anything with psy in it (psychiatrist, psychotic) has Greek roots.
They figure out -- because they try to spell words that have the letter Y -- that not all alphabets have the same sounds in them.
It's a good distraction for a lazy day. And frankly, after having heard my kids call my name a gazillion times, it's kind of nice to hear, "Mu omicron mu!" instead.