Ok, so at six weeks old with weather in the mid-70's during the day and around 60 at night, I decided it was time to introduce the chicks to the coop... and the big girls to the chicks. Last time I went through this process, I added a shelf to the coop to fit my wire dog kennel. This helped keep the run space beneath open for the big girls and kept the little ones up off the ground at night. It also keeps the big girls from roosting on top of the dog kennel and pooping on the babies' heads. I'll keep it this way for 2-3 weeks, with some supervised "play together" times as we progress. I set the babies down in the coop while I got things situated, and Opal came to investigate. I'm not sure what she thought of them, or what they thought of her... but they'll have time over the next few weeks to figure that out. I use pine shavings in my coop, but I'll use Koop Clean in the dog kennel... because, well, baby poo stinks!