Sand box

I have read it's a bad idea because they can consume too much sand and have troubles. If you can get some greens like lettuce or spinach or clumps of sod if your ground is unfrozen to peck at, also a short perch can keep them entertained.

 

X2

 

Not the fine silica sand. You want the untreated plain river sand. Not construction sand , either (as it can have chemicals in it).
Buy some chick gravel and put it in a cup. They will figure it out. The problem with them mistaking sand for food only happens when newly hatched. At that time, just put paper towels or that waffle weave drawer liner on the bottom of the coop. Then sprinkle a little bit of grit on top their food for a day or so. Not enough that it will impact their nutrition. Then after 2 days, put in a cup of chick grit. By then they have figured out where the feed is and will not mistake the grit for it. By the time they are old enough to move off the drawer liner or paper towel, hey have the grit and feed thing figured out and they can move to the river sand floored brooder.
https://www.backyardchickens.com/t/891051/the-science-of-feeding-grit-to-poultry
The 2nd page of the brochure in post #4...has the how and where feeding instructions.
Best,
Karen