By 2 - 3 weeks of age, chicks should have 2 s.f. of open space per chick. They double their size every week. I would also put them on shavings or something else for deep bedding. The water needs to be elevated to chest height, and it will be helpful if you do so with the feeder. Are you giving them grit? They need chick sized grit. As
@andreanar says, a nice big clump of sod will give them plenty of diversion as well as benefit their health. Sod, placed upside down will give them: first grit, first greens, plenty of minerals, perhaps a few insects and worms and seeds, first dust bath, plenty of games: king of the mountain, and keep a-way. By far the most important benefit is exposure to beneficial bacteria and fungi to give them a healthy gut and immune system, and first exposure to the pathogens they will encounter when they move outside. WAIT! DON'T PANIC! It's actually a GOOD thing for them to be exposed to cocci and other pathogens while they are young, and most preferably in the first 2 weeks of their lives, while their neonatal immune responses are the highest.
