The book warned us: at some point your chicks will get rambunctious enough that they will need roomier housing. ... The Cheeples need roomier housing. They act like wind-up toys on meth.
I brought a second box home from work, binder-clipped them together, and cut out a little portal. Greg built a ramp, but so far they have avoided it.
Later, I switched out the ramp for a perch. They still avoided it. After a couple of hours I got impatient and physically put them in it amid much screaming and crying. I don't recommend the impatient route. It attracts cats. Plus, crying chicks are just sad.
So the Cheeples stopped crying, and the smart ones hopped back in the old brooder box while their slower flockmates waited patiently for something to change. So I picked them up and showed them how to go through the portal.
Now they all avoid the new brooder box...except the Leghorns. They love hopping in there and having a quiet bite to eat then hopping back in the old box for some rowdy fun.