# 5.4: Enrichment

Difficulty Level: At Grade Created by: CK-12

## Enrichment 4-1: Teacher Activity Notes

Using a Bicycle to Demonstrate How Controllers Work

### PLAN

Summary

In this demonstration activity, teacher and students use a bicycle to show how a controller works. Feedback loops and delay are demonstrated. After the demonstration, students create diagrams of the bicycle control loop.

Objective

Students:

\begin{align*}\checkmark\end{align*} explain how the control system of the body regulates the exchange of \begin{align*}O_2\end{align*} and \begin{align*}CO_2\end{align*} gases.

Student Materials

• Activity Guide
• Activity Report
• Bicycle; Clothespins (3 or 4); Deck of cards

Teacher Materials

Arrange to have a bicycle in the classroom.

Estimated Time

One 50-minute period

Prerequisites and Background Information

Students should have completed Activity 4-1: How Does a Controller Work?

### IMPLEMENT

Step 1 Turn the bicycle upside down on its handle bars and seat. Be careful not to get your fingers or clothing near the spokes.

Step 2 Use clothespins to hold playing cards so they buzz against the spokes of the rear wheel.

Step 3 Start the rear wheel spinning and maintain at a fairly high speed (uniform pitch).

Step 4 Use the hand brake and pedal as necessary to maintain a constant speed.

Step 5 Discuss what happens with the class.

Step 6 Repeat Steps 3, 4, and 5, dividing the tasks with a group of four students. The controller listens to the buzz and tells the pedal turner when to pedal and the braker when to brake. The recorder records observations.

### ASSESS

Use the performance of the demonstration and the written answers on the Activity Report to assess if students can

\begin{align*}\checkmark\end{align*} explain and/or demonstrate how to maintain a constant speed on a bicycle.

\begin{align*}\checkmark\end{align*} explain how breathing is monitored and regulated in their bodies

\begin{align*}\checkmark\end{align*} define the terms: sensor, controller, controlled system, variable, feedback, and delay.

## Enrichment Activity 4-1: Using a Bicycle to Demonstrate How Controllers Work – Activity Report Answer Key

• Sample answers to these questions will be provided upon request. Please send an email to teachers-requests@ck12.org to request sample answers.
1. Can the pitch of the buzzing be kept even by just turning the pedal? Why?
2. Can the speed of the wheel be controlled by using both the pedal and the brake simultaneously? Why?
3. Is control easier or harder with four people? Why?
4. What happens when delay is added to a control system?
5. Below are parts of any control system. Explain what each one does and give an example of each from this activity or another control system.
1. sensor :
2. controller:
3. controlled system:
4. variable:
5. feedback:
6. delay:

## Enrichment 4-1 Activity Guide: Using a Bicycle to Demonstrate How Controllers Work (Student Reproducible)

Introduction

In this demonstration, teacher and students spin a bicycle wheel and the class investigates more about feedback.

Materials

• Activity Report
• Bicycle
• Clothespins (3 or 4)
• Deck of cards
• Paper
• Pencils

Procedure

Step 1 Turn the bicycle upside down on its handle bars and seat. Be careful not to get your fingers or clothing near the spokes.

Step 2 Use clothespins to hold playing cards so they buzz against the spokes of the rear wheel.

Step 3 Start the rear wheel spinning and maintain at a fairly high speed (uniform pitch).

Step 4 Use the hand brake and pedal as necessary to maintain a constant speed.

Step 5 Discuss what happens with the class.

Step 6 Repeat steps 3, 4, and 5, dividing the tasks with a group of four students. The controller listens to the buzz and tells the pedal turner when to pedal and the braker when to brake. The recorder records observations.

## Enrichment 4-1 Activity Report: Using a Bicycle to Demonstrate How Controllers Work (Student Reproducible)

1. Can the pitch of the buzzing be kept even by just turning the pedal? Why?

2. Can the speed of the wheel be controlled by using both the pedal and the brake simultaneously? Why?

3. Is control easier or harder with four people? Why?

4. What happens when delay is added to a control system?

5. Below are parts of any control system. Explain what each one does and give an example of each from this activity or another control system.

a. sensor

b. controller

c. controlled system

d. variable

e. feedback

f. delay

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