Looks like the brown one on the right might be a roo by the size of it's comb, can't really see the first barred rock's comb so I cant tell, and the last picture with the barred rock seems like a hen to me.
So what you wanna do, if the mamma hasn't done it already, is to show the chicks how to drink. You dip their beaks in water and after that they'll know.
Then you wanna make sure that the mamma isn't too aggressive with the single chick, if she is constantly ignoring it, and or pecking it...
In April, it will be the first time I have ever attended a poultry show, and possibly a poultry auction. I might be auctioning by Black Australorp cock (pictured in my avatar). I have no idea what to expect about buyers and their eye for birds, or have any idea of what to expect of judges...
Funny image of them at Thanksgiving eating some mashed potatoes and turkey.
And a front view of my show quality 25 week old (at photo taken) Aussie.
I don't have a good side view, I think I'll update my post once I do get a picture.
Looks like a hen to me. I have two Aussie roosters at 27 weeks old, mine have their greater sickle feathers and have had them since week 20. Your bird doesn't have a very red comb, so that looks more like a hen to me. If she's being rowdy in the coop with your other birds, that might just be her...
These are my two Black Aussies that I purchased from that hatchery in August at maybe 18-20 weeks at the photo taken.
This was them when they came in the mail.
They had another brother, and the hatchery gave me a White Leghorn also, but they both died within days of getting them. The other...
First day in BYC so forgive me of oversharing.
My first chickens are Black Aussies, yesterday they just turned 27 weeks old. They're both roosters and are fully mature, one is named Krule (my avatar) and the other is Kyle. Kyle is taller and thinner, but Krule holds himself as the top cock...