Signals in Motion

Rethinking a second text-heavy lesson by turning the nervous system into something students can physically model, test, trace, and troubleshoot.

In this chapter, you will see...

What stays protected

Nerves throughout the body • branching nerve-cell structure • connected network • signals between body and brain/spinal cord • sensation • response • structure → function • application to numbness and delayed feeling

What is still being tested

Whether the blood lesson becomes hands-on; whether the nerve text returns as the default; visual high-five versus hand squeeze; Vernier conductivity demo; reflex-hammer/force-probe activities; which experiments belong in the resource class before scaling.

Lesson 5: Signals in Motion

Why I am reluctant to teach two readings in a row—and how a human signal chain, reaction-time models, and selective direct instruction can make the nervous system easier to see.

By William Pirl | Unit 6.6: Injuries & Healing | PIRL Experimental

Lesson 5 creates a problem that has almost nothing to do with the quality of the lesson itself.

OpenSciEd asks students to look closely at nerve-cell images, read about the nervous system, participate in short sensory and signal-speed activities, and then return to the numbness and delayed return of feeling in the injured foot. It is a sensible two-day progression.

But if Lesson 4 has just ended with a blood reading, Lesson 5 asks students to turn around and do another reading-centered lesson almost immediately.

I hate the feel of that sequence.

The question is not whether students can read twice in a row. The question is whether the second reading is the best way to make a signal system feel alive.

The solution depends on what happened yesterday

This is where curriculum decisions stop being isolated lesson decisions. If I successfully rebuild the blood lesson into something hands-on, the nerve reading suddenly becomes more attractive. It gives the unit a change of pace and preserves a valuable literacy experience.

If the blood lesson remains reading-heavy, I am much more inclined to make nerves physical: students become the signal pathway, trace reaction sequences, or test response speed. The content target stays the same. The mode changes because the sequence needs it.

What OpenSciEd is trying to build

The published lesson is designed for two days. Day 1 focuses on structure: students revisit numbness and returning sensation in the foot, generate questions about nerves, and analyze microscopic nerve images. Day 2 focuses on function: students read about nerves, connect branching structure to signal transmission, experience touch and signal speed, and apply the ideas back to the injury.

The endpoint is intentionally limited. Students do not need to memorize the detailed anatomy of a neuron or the mechanism of electrochemical signaling. They need the bigger systems idea: branching cells form a network that moves information.

Nerve-cell structure → network → signal → sensation or response.

The published lesson already contains more activity than I remembered

It is easy to remember Lesson 5 as 'the nerves reading,' but the Teacher Edition is actually more varied than that. The learning-plan snapshot gives 20 minutes to microscopic nerve images, 18 minutes to scientific text, and another 16 minutes to discussion plus two short experiences.

That matters because my redesign is not a rejection of the OpenSciEd idea. In some ways, I have pushed farther in the direction the lesson is already pointing: if the concept is a communication network, let students inhabit the network.

Modification #1: Turn the class into a nervous system

One of my most successful substitutes is essentially a telephone game disguised as a nervous-system model—and a blood review disguised as trivia.

One student is the ear. A small group becomes the brain. Another student is the mouth. The remaining students form the pathway between them.

I hand the ear a blood-review question. The signal travels to the brain. The brain is allowed to use notebooks, which becomes an easy analogy for memory. The brain writes an answer on the back. The message then travels through the pathway to the mouth, who reads the answer aloud to me.

The class is reviewing blood while physically rehearsing the logic of the nervous system.

The relay works because every role has a job

We time the process and repeat it. Can the class get faster without losing accuracy? That creates a natural discussion about what 'speed' means in a communication system and what happens when the pathway is inefficient or broken.

I do not need the model to be anatomically perfect. I need it to make the direction and dependency of communication visible.

Why using blood trivia makes the activity stronger

The trivia questions are not incidental. They make the transition between Lessons 4 and 5 do curricular work.

Instead of spending the opening ten minutes verbally reviewing plasma, platelets, red blood cells, and white blood cells, the class has to retrieve that information while practicing the new nervous-system model. Review and new content are happening at the same time.

Modification #2: Be explicit about the five-step pathway

After the relay, I am comfortable using direct instruction. The activity gives students an experience; the lecture gives them a clean model to organize it.

The basic pathway I want students to be able to trace is simple:

Receptor → sensory nerves → brain/spinal cord → motor nerves → muscle response

I do not need students memorizing every neuron structure or every synapse. I need them to be able to explain how seeing, hearing, touching, or feeling something can lead to a coordinated response.

Modification #3: Break a familiar action into absurdly small steps

I have used an image of a boy catching a ball and asked students to break the action into as many steps as possible. The more they slow the event down, the more the nervous system appears.

• Light from the ball reaches the eyes.
• Receptors detect the visual information.
• Sensory signals travel toward the brain.
• The brain interprets speed, direction, and location.
• The brain selects a response.
• Motor signals travel toward the arm and hand muscles.
• Muscles contract.
• The hands move into position.
• Touch receptors provide new feedback when the ball arrives.
• The system adjusts grip and arm position.

A one-second action becomes a chain of communication. That is the point.

Modification #4: Use reaction-time games as a pathway puzzle

Online reaction-time tests work well for the same reason. Students click when a visual stimulus appears, or respond to an odd/even or simple-math prompt.

Instead of treating the score as the lesson, I ask students to explain everything that had to happen between the moment the screen changed and the moment their finger clicked.

The test becomes more useful when students compare tasks. A simple color change requires detection and response. An odd/even or math task adds interpretation and decision-making. The nervous-system model suddenly has somewhere for 'thinking time' to go.

Students can draw arrows or use cards to arrange the sequence. The same five-part model stays visible even when the task becomes more complicated.

The score is interesting. The pathway is the science.

The reading is still a perfectly good option

If Lesson 4 becomes a strong hands-on blood lesson, I may simply return to the OpenSciEd nerve reading. That would not be a retreat. It would be good sequencing.

I can still give every student the text even when we do not use it in class. Like the blood text, it can function as a reference for study guides, makeup work, newly created study hall, or students who want a second explanation.

What the text is supposed to accomplish

OpenSciEd's reading is not asking students for detailed neurobiology. It is trying to help them connect the unusual branching structure they observed to the job of receiving and transmitting signals between the body and brain.

That means several substitute media can reach the same target. A teacher-guided explanation can do it. A short video can do it. I used a Bill Nye nervous-system video successfully when I was away on a field trip. None of those choices is automatically superior.

Modification #5: Model signal transmission with a human chain

OpenSciEd includes a hand-squeeze chain: students join hands, one person initiates the squeeze, and the signal is passed down the line until the last student responds. The class can time the process and then discuss what happens when the pathway gets longer or is interrupted.

My hesitation is practical: hidden hand squeezes invite anticipation and cheating. Students can pass the signal before they actually receive it.

One modification I am considering is making the signal visible. Instead of squeezing a hand, a student receives a visual high five or other obvious gesture and then turns to pass the same signal to the next person.

That changes the sensory input, but it improves observability. Everyone can see whether the signal actually moved sequentially.

This year's pilots: bring real measurement into the lesson

I also own tools I have used successfully on myself but have not yet trusted to a full class.

Pilot #1: Vernier signal-conductivity probes

The Vernier equipment can make muscle activation or signal-related electrical activity visible as data rather than metaphor. Even as a teacher's demonstration, that could create a powerful bridge between 'nerves carry signals' and measurable electrical changes associated with muscle activity.

I would begin small. A resource class is the ideal place to learn the setup, identify procedural problems, and decide whether the visualization is clear enough to justify using it with larger classes.

Pilot #2: Reflex hammers and force probes

Reflex testing offers another route into rapid nervous-system responses. A reflex hammer can provoke a familiar knee-jerk response; a force probe could potentially quantify aspects of the resulting movement or muscle force.

The value would not be the medical novelty. The value would be asking students to distinguish a reflex pathway from a slower, deliberate reaction.

OpenSciEd vs. my rebuilt Lesson 5

What I am protecting, compressing, and still questioning

The version I want to teach this year

I would choose the version after I know what I am doing with Lesson 4.

A possible one-period Lesson 5

The bigger point

Lesson 5 reminds me that pacing is not only minutes. It is also texture.

Two readings can fit on the calendar and still feel repetitive. Two hands-on lessons can fit on the calendar and still leave students without enough time to organize what they learned. A well-designed sequence alternates demands: observe, read, move, model, explain, apply.

That means the best version of Lesson 5 cannot be selected in isolation. It depends on what Lesson 4 became.

I am not choosing between reading and hands-on. I am choosing the right tool for this point in the sequence.

Sources & design notes

Primary curriculum source: OpenSciEd, Unit 6.6, Lesson 5 Teacher Edition, “What do nerves do, and why are they in different parts of the body?” Version dated 2/9/22. Curriculum screenshots are excerpted from the user-provided Teacher Edition for commentary, comparison, and instructional analysis.

Established practice: human nervous-system / telephone relay with blood trivia, direct instruction, labeling/modeling, ball-catching pathway analysis, and online reaction-time activities. Prior substitute: Bill Nye nervous-system video. Active experiments: visible high-five signal chain, Vernier signal-conductivity demonstration, reflex hammers, force probes, and using the resource class as a pilot environment.

LESSON 5 | CONDENSED MODIFICATION GUIDE

Unit 6.6 • Injuries & Healing

PROTECT: branching nerve cells • network • signal pathway • sensation/response • structure → function • damaged pathway → lost feeling

RECOMMENDED TIMING

CUT FIRST: extended DQB review • investigation planning • every nerve image • full reading scaffold • both OSE mini-activities • lengthy reflex explanation • poster updates.

Adapted from OpenSciEd Unit 6.6, Lesson 5 • Teacher-use summary

Lesson 5: Practical Modification Guide

Nerves, Signals, Reaction & Response

What this lesson really needs to accomplish

Do not let vocabulary take over. Students need one durable model of nervous-system communication.

• Nerves are found throughout the body.
• Nerve cells have long branching structures.
• Those branches help create a connected network.
• Receptors detect stimuli.
• Sensory pathways carry information toward the central nervous system.
• The brain/spinal cord process or route information.
• Motor pathways carry signals toward muscles.
• Muscles create the observable response.
• Nerve damage can interrupt the pathway.

What I have done in the past

1. Human nervous-system telephone game

Students become the ear, pathway, brain, pathway, and mouth. Blood-trivia questions travel through the system; the brain uses notebooks as 'memory'; the mouth delivers the response. Time repeated trials.

2. Direct instruction after the model

Use the activity to create an experience, then explicitly teach the five-step pathway so students have accurate language for what they just modeled.

3. Catching-a-ball breakdown

Students take one familiar action and break it into tiny sensory, processing, signaling, and muscular steps.

4. Reaction-time tests

Students use a basic, odd/even, or math reaction test and explain every nervous-system step between the visual stimulus and the click.

What I am considering this year

1. Return to the text—if Lesson 4 becomes hands-on

The reading is still a sound lesson. Sequence matters: after a hands-on blood lesson, a guided nerve reading may provide useful variety.

2. Visible signal chain

Try a high-five or another visible cue instead of a hidden hand squeeze if anticipation/cheating makes the original chain unreliable.

3. Bill Nye or another short video

Useful as a substitute medium when the goal is efficient content delivery rather than practicing scientific reading.

4. Vernier conductivity / signal demonstration

Pilot with the resource class first. The demonstration is only worth scaling if students can clearly connect the data to nervous-system signaling or muscle activation.

5. Reflex hammer + force probe

Potentially useful for comparing reflexive and deliberate responses. Begin as a controlled teacher demonstration before designing a student lab.

My current recommendation

Use one 66-minute period unless you intentionally want to preserve the full OpenSciEd image-analysis and reading sequence. Let Lesson 4 determine the mode: if blood is text-heavy, make nerves physical; if blood is hands-on, the nerve text is a reasonable choice.

What to cut first

• Extended blood/DQB review.
• Full student-generated investigation planning.
• Analysis of every microscopic nerve image.
• Detailed comparisons with every blood-cell type.
• Full 1100L–1300L reading plus all scaffolds if using another content route.
• Both two-point touch and signal-speed activities.
• Extended reflex-arc explanation.
• Large Progress Tracker / DQB updates.

What not to cut

• Numbness and delayed return of feeling in the injured foot.
• Branching nerve-cell structure.
• Connected network idea.
• Signal movement into and out of the CNS.
• At least one physical or visual signal experience.
• Structure-function explanation.
• Application to damaged pathways and lost sensation.

One rule for a teacher new to the curriculum

Students do not need a tour of the nervous system. They need to be able to trace a signal.