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