A Question of Balance

Build Materials (For each team)

Required Materials

• Wooden dowels
• Plastic bowls or paper cups
• Wire
• Tape
• String
• Four canning jars or small empty boxes 

Testing Materials

• Scale
• Boxes of marbles, paperclips, or other items consistent in size and shape

Materials

• Scale
• Boxes of marbles, paperclips, or other items consistent in size and shape

Process

You’ll need to decide what the goal weight/count for each team is, based on the item (marble, paperclip) you select and the strength of the paper cups or other materials used.

Teams test their designs by running their system and “packaging” four products. Watch the packaging process, and also weigh all jars to make sure they are close to the goal weight or count. There will be some differences, but the difference should be no more than one or two marbles, assuming the weight is the same for each.

Design Challenge

You are a team of manufacturing engineers who have been given the challenge of designing and then building a manufacturing system to deliver a consistent weight or count of marbles or other items to a series of four boxes or jars.

Criteria

• Must deliver a consistent weight or count of marbles to a series of four boxes of jars

Constraints

• Use only the materials provided.

1. Break class into teams of 2-3.
2. Hand out the A Question of Balance worksheet, as well as some sheets of paper for sketching designs.
3. Discuss the topics in the Background Concepts Section.
4. Review the Engineering Design Process, Design Challenge, Criteria, Constraints and Materials.
5. Provide each team with their materials.
6. Explain that students must design and build a system to “manufacture” four packages (boxes or jars) of a product (marbles, paperclips, etc.) of equal weight or count. The idea is that their system will generate consistent end packages. Students may want to develop ramps or conveyor belts, tipping mechanisms, or other methods to deliver the candy to the final package.

   You’ll need to decide what the goal weight/count for each team is, based on the item (marble, paperclip) you select and the strength of the paper cups or other materials used.

   They should estimate the count variance they expect will result between the four jars/boxes using their manufacturing system.  What is the allowable or expected difference in weight or count between those four packages?

7. Announce the amount of time they have to design and build (1 hour recommended).
8. Use a timer or an on-line stopwatch (count down feature) to ensure you keep on time. (www.online-stopwatch.com/full-screen-stopwatch). Give students regular “time checks” so they stay on task. If they are struggling, ask questions that will lead them to a solution quicker.
9. Students meet and develop a plan for their manufacturing system.They agree on materials they will need, write/draw their plan, and present their plan to the class. Teams may trade unlimited materials with other teams to develop their ideal parts list.
10. Teams build their designs.
11. You’ll need to decide what the goal weight/count for each team is, based on the item (marble, paperclip) you select and the strength of the paper cups or other materials used. Teams test their designs by running their system and “packaging” four products. Watch the packaging process, and also weigh all jars to make sure they are close to the goal weight or count. There will be some differences, but the difference should be no more than one or two marbles, assuming the weight is the same for each.
12. As a class, discuss the student reflection questions.
13. For more content on the topic, see the “Digging Deeper” section.

Student Reflection (engineering notebook)

1. Did you succeed in creating a manufacturing system? If not, why did it fail?
2. Did you have to make changes from your written design when you were actually building the system? If so, what part of the system required the most changes in the construction phase?
3. Do you think that working engineers have to adapt their original plans during the manufacturing process? Why might they?
4. How did the actual weight or count between the four “packages” vary? How did this result compare to your pre production estimate?
5. What part of this process did you enjoy the most? Why?
6. What idea that you saw implemented in another team’s work did you find most inventive? Why?
7. Did you find that there were many designs in your classroom that met the project goal? What does this tell you about engineering plans?
8. Did you find that working as a team made this project more successful? If not, why not?  If so, explain.
9. In a real manufacturing environment, do you think the design of the “package” — the box, jar, or bag — is developed before, after, or at the same time that the product is developed?  What would make most sense to you?  Why?

The lesson can be done in as little as 1 class period for older students. However, to help students from feeling rushed and to ensure student success (especially for younger students), split the lesson into two periods giving students more time to brainstorm, test ideas and finalize their design. Conduct the testing and debrief in the next class period.

Scale Applications
Scales Have Many Uses

Scales are used in many applications — beyond determining personal weight. They are an integral part of many systems, as the weight of products or components impacts the costs of products or services. For example, postal systems all over the world base the cost of delivery on the weight of the letter or package being transported. Grocers and fruit markets use scales to determine what to charge for fruits, vegetables, nuts, grains, and spices. In these examples, the weight may be a little off one way or the other without causing any difficulty. You may get an extra nut or two, or end up with a pinch less spice without implications.

Manufacturing Engineering

For manufacturing engineers, particularly those in the pharmaceutical industry, it is critical for weights or products or components to be accurately measured prior to packaging. Drug manufacturers must be sure the dose is exact — close is not good enough! Safety is a top manufacturing consideration!

Manufacturing engineers are involved with the process of manufacturing from planning to packaging of the finished product. They work with tools such as robots, programmable and numerical controllers, and vision systems to fine tune assembly, packaging, and shipping facilities. They examine flow and the process of manufacturing, looking for ways to streamline production, improve turnaround, and reduce costs. One of the measures they focus on is weight. They sometimes use cameras to count the number of products that go into a package, such as the number of cookies in a box, but they very frequently use scales to make sure that the promised amount of candy, cereal, or even nails is delivered in a box. There are many websites that show working manufacturing systems — visit some of these to see how different systems work! For example Jelly Belly jellybeans are poured into a hopper during their manufacturing process. The hopper feeds them into a scale system which weighs and dispenses the precise amount of jelly beans into different types of packaging including bags, boxes, and jars.

Recommended Reading

• Manufacturing Engineering and Technology (ISBN: 0131489658)
• Scales and Balances (ISBN: 0747802270)

Writing Activity

Write an essay or a paragraph about the implications of automation processes on society.

Alignment to Curriculum Frameworks

Note: Lesson plans in this series are aligned to one or more of the following sets of standards:

• S. Science Education Standards (http://www.nap.edu/catalog.php?record_id=4962)
• S. Next Generation Science Standards (http://www.nextgenscience.org/)
• International Technology Education Association’s Standards for Technological Literacy (http://www.iteea.org/TAA/PDFs/xstnd.pdf)
• S. National Council of Teachers of Mathematics’ Principles and Standards for School Mathematics (http://www.nctm.org/standards/content.aspx?id=16909)
• S. Common Core State Standards for Mathematics (http://www.corestandards.org/Math)
• Computer Science Teachers Association K-12 Computer Science Standards (http://csta.acm.org/Curriculum/sub/K12Standards.html)

National Science Education Standards Grades 5-8 (ages 10 – 14)

CONTENT STANDARD A: Science as Inquiry

As a result of activities, all students should develop

• Abilities necessary to do scientific inquiry
• Understandings about scientific inquiry

CONTENT STANDARD B: Physical Science

As a result of their activities, all students should develop an understanding of

• Motions and forces

CONTENT STANDARD E: Science and Technology

As a result of activities in grades 5-8, all students should develop

• Abilities of technological design
• Understandings about science and technology

CONTENT STANDARD F: Science in Personal and Social Perspectives

As a result of activities, all students should develop understanding of

• Science and technology in society 

National Science Education Standards Grades 9-12 (ages 14-18)

CONTENT STANDARD A: Science as Inquiry

As a result of activities, all students should develop

• Abilities necessary to do scientific inquiry
• Understandings about scientific inquiry

CONTENT STANDARD B: Physical Science

As a result of their activities, all students should develop understanding of

• Motions and forces

CONTENT STANDARD E: Science and Technology

As a result of activities, all students should develop

• Abilities of technological design
• Understandings about science and technology

CONTENT STANDARD F: Science in Personal and Social Perspectives

As a result of activities, all students should develop understanding of

• Science and technology in local, national, and global challenges 

Next Generation Science Standards Grades 3-5 (Ages 8-11)

Engineering Design

Students who demonstrate understanding can:

• 3-5-ETS1-1.Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.
• 3-5-ETS1-2.Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
• 3-5-ETS1-3.Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved. 

Next Generation Science Standards Grades 6-8 (Ages 11-14)

Engineering Design

Students who demonstrate understanding can:

• MS-ETS1-2 Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.

Principles and Standards for School Mathematics (ages 6 – 18)

Number and Operations Standard

• Understand numbers, ways of representing numbers, relationships among numbers, and number systems
• Compute fluently and make reasonable estimates

Measurement Standard

• Understand measurable attributes of objects and the units, systems, and processes of measurement
• Apply appropriate techniques, tools, and formulas to determine measurements

Representation

• Create and use representations to organize, record, and communicate mathematical ideas
• Use representations to model and interpret physical, social, and mathematical phenomena

Common Core State Standards for School Mathematics: Content (ages 7-10)

Measurement and Data

• Solve problems involving measurement and estimation.
• Math.Content.3.MD.A.2Measure and estimate liquid volumes and masses of objects using standard units of grams (g), kilograms (kg), and liters (l).1 Add, subtract, multiply, or divide to solve one-step word problems involving masses or volumes that are given in the same units, e.g., by using drawings (such as a beaker with a measurement scale) to represent the problem.2

 Standards for Technological Literacy – All Ages

The Nature of Technology

• Standard 1: Students will develop an understanding of the characteristics and scope of technology.
• Standard 2: Students will develop an understanding of the core concepts of technology.
• Standard 3: Students will develop an understanding of the relationships among technologies and the connections between technology and other fields of study.

Design

• Standard 9: Students will develop an understanding of engineering design.
• Standard 10: Students will develop an understanding of the role of troubleshooting, research and development, invention and innovation, and experimentation in problem solving.

Abilities for a Technological World

• Standard 12: Students will develop abilities to use and maintain technological products and systems.
• Standard 13: Students will develop abilities to assess the impact of products and systems.

The Designed World

Standard 19: Students will develop an understanding of and be able to select and use manufacturing technologies.

You are a team of manufacturing engineers who have been given the challenge of designing and then building a manufacturing system to deliver a consistent weight or count of marbles or other items to a series of four boxes or jars.

Research/Preparation Phase

1. Review the Student Reference Sheet. If possible visit some of the virtual manufacturing websites.

Planning as a Team

2. Your team has been provided with some materials by your teacher including wooden dowels, plastic bowls or paper cups, wire, tape, string, four canning jars or small empty boxes. You also have a large quantity of a “product” which may be marbles, paperclips, or other items your teacher has selected. Your job is to design a manufacturing system that will weigh a set amount of the product and deliver it to four jars or boxes. You need to make sure the weight or count is on target, and that it is consistent between those four packages.
3. Start by meeting with your team and agreeing on a system design. Be creative and enjoy the process!
4. Estimate the count variance you expect will result between the four jars/boxes using your manufacturing system. What is the allowable or expected difference in weight or count between those four packages?
5. Write or draw your plan in the box below (or on a separate piece of paper).

Construction Phase

5. Construct your manufacturing system.
6. Take a look at the systems created by other class teams.
7. Run your system and “package” four products. Your teacher will weigh each package for your team so you can see how well your system worked.
8. Evaluate your teams’ results, complete the evaluation worksheet, and present your findings to the class.

Use this worksheet to evaluate your team’s results in the Build a Big Wheel lesson:

1. Did you succeed in creating a manufacturing system? If not, why did it fail?

2. Did you have to make changes from your written design when you were actually building the system? If so, what part of the system required the most changes in the construction phase?

3. Do you think that working engineers have to adapt their original plans during the manufacturing process? Why might they?

4. How did the actual weight or count between the four “packages” vary? How did this result compare to your preproduction estimate?

5. What part of this process did you enjoy the most? Why?

6. What idea that you saw implemented in another team’s work did you find most inventive? Why?

7. Did you find that there were many designs in your classroom that met the project goal? What does this tell you about engineering plans?

8. Did you find that working as a team made this project more successful? If not, why not?  If so, explain.

9. In a real manufacturing environment, do you think the design of the “package” — the box, jar, or bag — is developed before, after, or at the same time that the product is developed? What would make most sense to you?  Why?