![Knox says cardboard is one of children's top 5 play objects. Others include dirt, string, and paper tubes. (Flickr photo/margaret)](https://www.kcaw.org/wp-content/uploads/2015/03/Cardboard_play_margaret-300x239.jpg?x32562)
Knox says cardboard is one of children’s top 5 play objects. Others include dirt, string, and paper tubes. (Flickr photo/margaret)
Knox says cardboard is one of children’s top 5 play objects. Others include dirt, string, and paper tubes. (Flickr photo/margaret)