thanks for your comments! i've already started an adult sized flap hat --my 19 yo daughter requested it
i make the flaps first, on double pointed needles, (you'll need 3 needles to knit, 2 to leave the flaps on) i just leave a tail, and then end teh flaps. then after you cast on a bit on circular needles, knit in teh first flap, then cast on more, then knit in teh second flap. you have to be careful, which side is knit and which is perl...on my first try, the hat was garter and the flap was stockinette. now i find if you position teh flap so that teh stockinette side is "inwards" as you knit it onto the circular, it will turn out OK (eg on circular, the stockinette side is inside...)
thanks for the pattern link!