Rearrangement reaction
Sometimes chemists draw diagrams with arrows that show how electrons are transferred between bonds during a rearrangement reaction.  Many organic chemistry text books have such diagrams.  But they do not tell the full story of the reaction mechanism. The actual mechanism of a rearrangement with an alkyl group moving is for the group to slide smoothly along a bond, not ionic bond-breaking and forming. One example of this is the Wagner-Meerwein rearrangement: