Thursday October 29, 2026 Green
Homework 98-107 and worksheet
Circle: If you could instantly send one message to every neuron in your body, what would you tell them to do? For example-
Never feel tired again.
Make me remember everything I study.
Make me faster or stronger.
Stop me from getting nervous before a test.
Let me understand any language.
Make me fall asleep instantly.
Activity: Finish True or False questions
Follow up questions for groups:
How does your brain communicate with your hand when you decide to raise it?
How does your brain know that you touched something hot?
How can a message travel from your brain to your toes so quickly?
Domino Activity: Your brain doesn't send text messages or use tiny wires. It uses specialized cells called neurons that communicate through electrical and chemical signals. Today, we're going to model how one of those signals travels.
Challenge: Using dominoes to model how a neural signal travels along an axon.
Round 1: Build the signal
Put students in groups of 3–4.
Give each group 15–25 dominoes.
Have them arrange the dominoes in a line with enough space for each domino to knock over the next one.
Ask one student to tip the first domino.
Have the group observe what happens from beginning to end.
Ask students to discuss:
What started the chain reaction?
Did the first domino physically travel to the end of the line?
What actually moved down the line?
Why did the chain reaction stop when it reached the last domino?
Round 2: Introduce the threshold
Now arrange the dominoes so that a small push does not start the entire chain, but a sufficient push does.
A neuron must reach a particular threshold to generate an action potential. In a neuron, this is not simply a matter of pushing harder; it involves changes in electrical voltage across the cell membrane that open voltage-gated ion channels.
Round 3: Break the signal
Have students deliberately leave a large gap between two dominoes.
What happened to the signal?
What might happen if a neuron could not successfully transmit its message?
Does a real neuron work exactly like this?
Domino model has limitations. Dominoes physically fall and stay down, while a neuron generates an electrical signal that is regenerated along the axon. The neuron does not need to knock down a series of permanently falling parts.
How does this relate to an actual neuron? 2-Minute Neuroscience: The Neuron
Student vocabulary investigation
Term:
Clue to help students figure it out
Neuron
The specialized cell that sends and receives information
Dendrites
The branches that receive incoming signals
Cell body (soma)
The part that contains the nucleus and integrates incoming information
Axon
The long extension that carries the action potential away from the cell body
Myelin sheath
Insulation around some axons that helps signals travel faster
Threshold
The membrane voltage that must be reached to trigger an action potential
Action potential
A brief, rapid change in membrane voltage that propagates along the axon
Depolarization
The membrane voltage becomes less negative, primarily because sodium ions enter the neuron
Repolarization
The membrane voltage moves back toward its resting level, primarily as potassium ions leave
Refractory period
A brief period when the neuron cannot fire normally again, or requires a stronger stimulus
Synapse
The junction where a neuron communicates with another cell
Neurotransmitter
A chemical messenger released by a neuron that can affect a receiving cell
For the first domino to fall...
The important idea is that an action potential is an all-or-none event. Once threshold is reached, the neuron generates a full action potential rather than a smaller one. Stronger stimulation can increase the frequency of action potentials, rather than increasing the size of each individual action potential.
Point to remember: Every time you move, feel something, remember a fact, or react to a sound, neurons are communicating. The action potential is one of the fundamental ways your nervous system makes that communication possible.
Connection: Revisit the domino model when you introduce synapses and neurotransmitters. “If the domino chain represents the axon, what happens when the signal reaches the end? Does the next neuron get knocked over directly, or does something else have to happen?” This sets up the distinction between electrical signaling within a neuron and chemical communication across most synapses.
