![CANADA-VANCOUVER-EXHIBITION-"MATH MOVES!"](136661385_15072535870931n.jpg)
A child plays with an exhibit describing the concept of frequency during the "Math Moves!" exhibition at Science World in Vancouver, Canada, Oct. 5, 2017. The "Math Moves!" is Vancouver Science World's latest exhibition, in which visitors can learn different math theories and concepts with interactive exhibits. (Xinhua/Liang Sen)