how do you spell "ok"?

TUESDAY, FEBRUARY 10th - 2009

When I pulled up at my mom's today, this is the first thing I noticed:

Her pretty flowers are in bloom.  They cheered me up, so I took a picture of them.  I especially love the dark purple ones.

My favorite thing that happened today:

Joe was sitting at the table in the family room doing homework while I was cooking dinner.  He was working on a paragraph that he was supposed to write using his vocabulary words.  He shouts at me, "mom, how do you spell ok"?  My reply: "um...O,... K."

Now that I think about it, you also spell it "okay".  Hmm... I wonder which is right.  How do you spell "ok"?