What is the definition of axial symmetry in the fourth grade mathematics of People's Education Press?
There is no special definition of symmetry in primary school mathematics books, but the following explanation is given for axisymmetric figures: when a figure is folded in half along a straight line, the figures on both sides of the crease can completely overlap, which is called axisymmetric figures. The straight line where the crease lies is called the axis of symmetry of this axisymmetric figure.