In this video I want you to make multiple predictions about what will happen to the brightness of the lamps when the switch is closed versus when it is open. Now go ahead and make your first prediction. Now that you have made your first prediction, we are going to look at this bed simulation here. What I would like you to do is focus on these two light bulbs here that are parallel to each other. I am going to turn on the switch now. You can see that the electrons are moving through these bulbs that have the same resistance at the same speed. Now what I am going to do is increase the resistance of the upper bulb and I want you to pay attention to what happens to the speed of the electrons going through this upper bulb versus the lower one. Now to increase the difference between the resistance of these bulbs even more, I am going to decrease the resistance of the lower bulb. And now you can see that the electrons are clearly moving much faster right now through the lower bulb that has a lower resistance compared to the upper bulb that has a higher resistance. In general, this suggests that in parallel combinations as the difference between the resistance of the two paths increases, a greater fraction of the current will flow through the path of lower resistance. And for larger differences, this means that almost all of the current will be going through the path of lower resistance. Okay, now that you've looked at the simulation, I want you to go ahead and refine your prediction if needed. So the open switch in the circuit is basically like having a resistor or a light bulb with a really large resistance. And so the electrons won't be wanting to go through that path because there is this path that has a much lower resistance. And then having the switch closed is like having a light bulb with a resistance of zero. So now we have this path of no resistance. And it's much easier for the electrons to go through a path that has no resistance. So they won't be going through this lower path that has a light bulb in it.