Hey Kotiya,
Are these the same birds from your other post? Being that they're only six weeks old, I'd say that the closest one is a pullet and the other two are boys. The "growth spurt" for CX's is from week 5 - 9 roughly. The growth is just phenomenal. I'd be willing to bet that at 8 weeks old, you would have no doubt. I just went out and compared your photos with my meaties and I'm pretty sure you've got two boys and one girl, unlike what I responded in your other thread. It's really hard to tell until after they've hit their growth spurt for a while then it's blatantly obvious. My meaties are pushing 14 weeks now so I've known for a while. I'm just seeing if free ranging them for a few weeks before processing will alter the taste of the meat.
How many meaties do you have? Perhaps you could use some different flock members to satisfy the 4H requirements.
Dan