Article
Khan Academy

Khan Academy: Neuron Action Potentials: The Creation of a Brain Signal

For Students 9th - 10th
Explains how neurons work during the formation and transmission of brain signals.
Unit Plan
OpenStax

Open Stax: Anatomy and Physiology: The Function of Nervous Tissue

For Students 9th - 10th
Learn here about how nervous tissue is capable of communicating within the nervous system.
Unit Plan
OpenStax

Open Stax: Anatomy & Physiology: The Sensory and Motor Exams

For Students 9th - 10th
Students learn the arrangement of sensory and motor regions in the spinal cord in order to understand a sensory and motor exam. They will also understand the clinical indications of common reflexes.
Handout
University of Wisconsin

The Why Files: Bolt on Brain Repairs

For Students 9th - 10th
A general discussion of nervous system stem cells that lead to the neurons that make up the central nervous system. Decent site that is barely tangential to neurons in general.