Partridge are easier to sex with silkies, as females have specific colouring. Males will have streamers - some had them at the breeder's at this age. I've also noticed that the boys had a more pronounced comb. Now I say that they are much harder to sex, but certain behaviours stick out for boys at this age as well. The boys stood taller, were more outgoing and fought with eachother more than the girls. I have 10 silkie chicks that are a week old, and I have one pegged as a cockerel based on attitude alone. Time will tell if my suspicions were right or not.
The one staring at you has a big personality and isn't as afraid as some of the others. I'll be keeping track of the growth to see if I was right or not.