demonstrations:nerve_speed_relay
Nerve Speed Relay
Materials: ★☆☆ Easy to get from supermarket or hardware store
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: The Brain and Nerves
Alternative titles: Nerve Transmission Test
Summary
This demonstration measures how quickly nerves transmit signals in the human body by setting up a relay line of participants who respond in sequence. The activity illustrates the concept of reaction time and the speed of nerve impulses.
Procedure
- Arrange a group of participants standing side by side in a line or sitting in chairs.
- Have each participant place one hand on the shoulder, knee, or arm of the person next to them.
- Designate the first person in line to start the signal (for example, by squeezing the next person’s hand or tapping their shoulder).
- Each person quickly passes the signal along the line as soon as they feel it.
- The last person in the line raises their hand or calls out when they receive the signal.
- Use a stopwatch to time how long the signal takes to travel through the line.
- Divide the total distance by the total time to estimate the average speed of the nerve signal through the group (not the actual nerve speed, but a model of how signals move).
Links
Connect the Neurons: A Classroom Activity - BrainU Videos:
Variations
- Compare times using different group sizes.
- Try different types of signals (hand squeeze, shoulder tap, word relay) and see which is fastest.
- Race two lines of participants to see which group relays the signal faster.
- Test if practice makes the group faster over multiple trials.
Safety Precautions
- Ensure participants do not hit or push too hard when passing the signal.
- Keep the demonstration in an open space to avoid tripping or bumping hazards.
- Remind participants to stay alert and focused on their turn to avoid delays.
Questions to Consider
- How does this model demonstrate the way nerves transmit information? (It shows how signals move from one “neuron” to the next in a chain.)
- Why is this slower than actual nerve impulses? (Real nerve impulses travel at up to 120 m/s, while human reactions add delay at each step.)
- What factors affect how quickly the signal moves down the line? (Attention, speed of response, number of people in the line.)
- How might repeated trials change the results? (Practice can improve reaction time, reducing delays.)