Hen/Roo game has a lot of rules. There are certain traits that cockerels will have at prepubescent ages that pullets are less likely to have (large red combs and wattles, namely), and there are certain colorations that only females can have that males never ever will (look up silver duckwing pullet and cockerel and wheaten pullet and cockerel for some examples). By 10ish weeks, you should start to see sex-specific colorations -- males of Teddy's coloration will have dark, glossy feathers on their shoulders, back, and tail. Pullets will be uniform across their body. Males will begin to grow in their long pointed saddle feathers, which on a chicken of Teddy's coloring will also be dark and glossy compared to the lighter brown of the body.well then, shows how little I know!