when my chicks were that age i began letting them out every once and a while to forage. the girls can also help with this by helping you to watch them. when they're that young its neccasary to keep an eye on them. something that might be fun and help socialize them is have the girls sit on the ground and then herd them twards them. you can even give them some feed to hold out for the babies.
for me thats just something fun that the chicks like. Fierlin1182 covered most of it. just make sure that if they are outside that the coop is 100% predator proof and there are no areas where the chicks can get out. when i first moved my chicks outside there was a place where they all got out that i didn't see. i lost almost half of them to the cats(i have 9 cats so they took a lot). make sure you double and triple check the coop and fence over any posible holes. if the chicks don't get out, the predators will get in.