An example of a simple series circuit is one where we have a voltage source and a resistive element (i.e., light bulb, heating element, or resistor) that is connected in a single enclosed path by conductors (i.e., copper wires). Theoretically, electrons travel from the voltage source through the copper wiring through some resistive element and back to the voltage source. The current (q/t) is the same in all parts of a series circuit. For every electron that leaves the voltage source there is an electron instantaneously returning to the voltage source. This does not have to be the same electron that initially left the voltage source. The reason for this is that once electrons leave the voltage source, they encounter opposition (resistance) from the conductors and resistive elements. Free electrons move from atom to atom. When a free electron leaves one atom, it is replaced by another electron. This process continues from atom to atom until the last electron in the chain returns to the voltage source.
One analogy to this process would be to line up five or six billiard balls with one ball touching the next one. Now, if that series of balls is struck very hard on one end by an external force, (i.e., hammering device, another billiard ball, etc.) one ball on the opposite end of the series moves instantaneously across the surface (which could offer opposition, friction, or resistance). This analogy could be modified if several balls were placed end-to-end in an enclosed circular tubing.
The above process could be rapidly repeated by a hammer device.
1)The analogy to voltage would be the hammering device.
2) The analogy to current flow or electron flow would be the moving billiard balls.
3) The analogy to resistance or opposition would be friction from the lining of the tubing.
Douglas
Reference
Ostdiek, V. J., Bord, D. J. (20170101). Inquiry into Physics, 8th Edition. [[VitalSource Bookshelf version]]. Retrieved from vbk://9781337515863