A boy visits Shed aquarium with his mother as his school was closed because of the frigid weather, in Chicago, the United States, on Dec. 7, 2014. Shedd aquarium offered Illinois' residents free general admission into its original galleries on Wednesday. The Museum of Science and Industry and other museums also opened freely and hosted the "School Days Out" programs so that the children have warm places to go during cold snap. (Xinhua/He Xianfeng)