Been feeding dried mealworms to the chucks for some time, scatter them on the grass in the paddock over quite a wide area, keeps them occupied for some time seeking them out, as they are dry I know they won't crawl away and hide (hide...lol)
I have a video somewhere of the chucks running down the paddock when they see the mealworm bag!

Found a useful supply at dried mealworms for Chickens Wild Birds Hedgehogs Fish and Reptiles