In module 2.2, I had a hard time understanding the section where it talks about the different phases of the action potential of a neuron.  I would say most of us know about the neuron because most of us have studied neurons in grade school, but I don't think we have ever seen these processes a neuron goes through that were mention in 2.2.  I now understand that the hyperpolarization is a change in the membrane of a neuron that makes it more negative following the generation of the action potential. During this process, the sodium and potassium ions are redistributed by the Sodium-Potassium Pump.  While the action potential is happening, it goes all the way to its peak which we call the threshold and that is where the windows that are letting the potassium and sodium ions in snap shut and goes to the resting potential, and wait until the next action potential starts to develop.