"Ahu" are stone platforms on which many moai sit. There are 313 known ahu and 125 of these carry moai. The biggest, Ahu Tongariki is 220 m (720 ft), and had the most (15) and tallest moai.
Libraries allow children to ask questions about the world and find the answers. And the wonderful thing is that once a child learns to use a library, the doors to learning are always open.