I have put a new toy in the brooder every day for them to investigate. Usually a cat toy. One day a ball with a bell in it, the next day a small soft stuffed toy, the next day a hanging parrot toy, a small mirror the next day etc. I have about 8-9 toys and change them out daily (mainly to clean the nasty off). Some toys they like, some they hate, some they ignore but just a mild change in placement and their surroundings gives them some thing to do. They like to put their beaks on everything.
I also may dig up a clump of grass with dirt still attached and give that to them, though this may not be an option for you but mine truly love it.
I do not put mine outside in a pen until they are about 4 weeks old. They are such nasty brooder babies I can't stand it by 2 weeks old!