I placed large logs in the run and rotated them daily. The girls love to peck at the bark and climb on it. When I turn it daily, there are usually several little bugs which are quickly devoured. I have also been known to hang pieces of fruit (apple, grapes, strawberries) on a string and they have quite a time chasing it around. A simple small pile of hay will entertain.
Awesome time to start teaching them HOW to play with toys. Start with small balls and then add little bit bigger every few days till its a small beach ball size. Perches in their run are important. Hanging safe grass, weeds, veggies like a pinata is alot of fun. Tin plates or mirrors is fun. Look at birds toys and think of how to convert it to chicken toys. Be careful of hanging something like a necklace that they could get tangled up in. Parakeet size is easier for them to handle then large bird toys because of their beak size. Make sure it is strong plastic that wont break. Use rope, or string, that is safe for birds. There are videos on chickens playing with balls and other toys that you can watch. Take a small coke bottle -- make it hard by carefully pouring boiling water in it- put 3 or 4 holes all around it -- fill with scracth -- and let the have at it.