from this pattern here.
I wanted to make the boy version for a little boy who will be 8 by the holidays and I found that the child version would be a little too snug after trying it on my almost 9 year old daughter.
To make it a little bigger I just went up to a 5.50 hook, I didn't need it too much bigger so just going up that half size did the trick.
It fits great and actually has a little room in it as well. :)
I changed the last two rounds of this one as well by doing:
ch 2 and hdc around, join like the rest of the hat
ch 1 and sc around, join like the rest of the hat.
This post will be going into my Spring into the Holidays 2012 Series as well.