I try to use the most natural methods of raising my animals as possible. Little chicks go out with their moms almost immediately and do exactly what she does. (except lay eggs, the darn slow pokes)
I find myself now with lots of little ones and it is nippy out so I have moved them to a big booder pen in the coop and they are under the heat lamp in the shavings, hay and a little dirt I brought in, "sunning" themselves. Bless them.
I haven't seen mine do it, but at the feed store, there was a pullet that I was sure was dead, so I picked it up and it didn't move. Then about 3 seconds later it opened it's eyes and freaked out and flew away. Funny!
My first hatch and my hens first hatch are just 4 days old now and they go out into the sun everyday with mama and lay in the dirt. It was SO funny, on their 2nd day she took them out with her (an enclosed pen of course) and she took a sun bath, laying out with foot & wing stretched out, then the 2 day old chicks copied her and did the same. I couldn't believe it! I think letting them do it naturally with the hen is the best also and she must thinks it's okay because she heads out everyday, comes in mid-day when its hot and they all nap, then she's back out with the chicks until just before sundown. They all seem very happy & healthy!