Tallest Paper Tower Challenge for Grades 9-12

Background Information for Teachers

Throughout the world, engineers have designed a wide variety of observation towers in different shapes and sizes (Figure 1). Unlike regular buildings and skyscrapers, which typically have rooms (offices, apartments, etc.) on every floor, observation towers may have a mostly "hollow" structure with an observation deck on top. Other similar structures that have a hollow frame with a heavy load at the top include water towers and radio towers (Figure 2). You can download a Towers of the World Slideshow for more pictures.

Image Credit Image Credit Image Credit Image Credit
Figure 1. From left to right: the Space Needle (USA), the Pitampura TV tower (India), the Eiffel Tower (France), and the CN Tower (Canada).

Image Credit: Wikimedia commons user G-man / Public domain Image Credit: Wikimedia commons user Freekhou5 / Creative Commons Attribution-Share Alike 4.0 International
Figure 2. Radio towers (left) and a water tower (right).

The 2021 Engineering Challenge is inspired by towers like those in Figures 1 and 2. As shown in the following video, the goal is for students to build the tallest possible tower using only paper and tape, but the tower must also support a can of food at the top.

https://www.youtube.com/watch?v=dJr2DJRKy5c

You can use this project to explore several topics in physics and engineering with your students. For example:

• Beams are long, skinny elements used to make many structures like towers and bridges. Multiple beams can be combined to make trusses. Certain truss shapes can be very strong. Can your students identify any trusses in Figures 1 and 2?
• An object that is being "squished" is in compression and an object that is being pulled on is in tension. Beams can be in either tension or compression, depending on how a tower is designed.
• Sometimes towers include ropes, cables, or chains as part of the design. These parts can only be in tension (think about what happens if you try to "push" a rope), but they can still be useful. For example, the long cables connected to the top of the radio towers in Figure 2 are called guy wires. They are anchored to the ground and prevent the tall, skinny towers from falling over.
• The shape of a beam can dramatically affect its strength. For example, it is very easy to bend a flat piece of paper. It becomes much harder to bend the paper if you fold it in half multiple times or roll it into a tube. This resistance to bending is determined by the beam's cross section. For example, the cross section of a flat piece of paper is a (very thin) rectangle. This rectangle bends very easily in the thin direction. The cross section of a piece of paper rolled into a tube is a circle. An I-beam (where the cross section looks like a capital letter I) is a common shape used in many structures.

You can also use this project to demonstrate the engineering design process. It is unlikely that your students' towers will work perfectly on the first try—they might even collapse! Your students might need to iterate by testing and tweaking their designs multiple times so they can continually improve them. You can use this video to review the steps of the engineering design process with your students.

https://www.youtube.com/watch?v=fuwGvZ-eOrc

Additional Background Links

• Tension and Compression: Two Forces Every Bridge Knows Well, HowStuffWorks
• Mini-Activity: Toothpick Truss, PBS
• The Engineering Design Process, Science Buddies

Prep Work (15 minutes)

• Gather all the construction materials in a central location for students.
• Print the Student Worksheets if you will be using them (one for each student, not student group).
• Optional: Assign the Introductory Video for your students to watch before class.

Engage (5 minutes)

Introduce the challenge to your students. Explain that the challenge is inspired by the real-world engineering design problem of building an observation tower. The tower should be as tall as possible and must support a heavy weight at the top. In order to minimize cost, the tower should also use as little material as possible for construction, without sacrificing safety or stability. A final score is calculated for each tower based on these criteria. For the project, students will build a model tower using paper and tape. Show your students the introductory video:

https://www.youtube.com/watch?v=dJr2DJRKy5c

Then, go over the Student Worksheet, including the rules (also listed below).

Optional: Show your students the Towers of the World Slideshow. You can also have students do their own research online to look for pictures of different towers.

Image Credit Image Credit: Ben Finio, Science Buddies / Science Buddies Image Credit: Ben Finio, Science Buddies / Science Buddies
Figure 3. Three examples of paper towers that comply with the contest rules.

Explore (1-2 hours)

1. Background research: Students should do background research about different types of tower designs, as well as structural elements like trusses and beams. This information will help them design their towers.
2. Preliminary testing: Before they start building a tower, students should investigate how basic structural elements can be made from the materials they have available. For example, what cross-sectional shape (circle, square, C-channel, etc.) makes the strongest beam from a piece of paper? What is the best way to form joints to connect beams?
3. Design: Based on their background research, preliminary testing, and constraints for the project, students should sketch at least two potential designs for their towers. If they are working in a group, each student can start by drawing their own ideas, then they can compare designs. Before proceeding, students should agree on a single design to build. The design they choose can include a combination of features from multiple designs.
4. Build: After agreeing on a design, students should plan out how they will build and test their tower, then start building. Even if they plan carefully, things might not work out as expected. They might encounter problems when building, and need to go back and change their design. Remind students that this is OK!
5. Test: After building, students should test their tower by carefully placing the can of food on top. They should carefully observe their tower to look for weak spots or ways to improve it. Do any parts of the tower sag or buckle? How could they improve the design to make these parts sturdier?
6. Evaluate: Based on their testing and observations, students should evaluate their solution in the context of the design criteria and trade-offs. For example, is it possible to make their tower taller? How much more paper would it require to do so, and would the end result be an increase or decrease in their final score? Is it possible to reduce the amount of paper used in a tower of the same height? Would increasing the height further dangerously reduce the tower's stability?
7. Iterate:: After evaluating their design, students should iterate to try and improve it to get a higher score. This could consist of modifying the existing tower or building a new one. Remember that only paper used in the final design counts toward the paper limit, so students can build as many towers as they want.

Reflect (20 minutes)

Once all students have finished building their towers, have a class-wide competition to calculate official scores.

1. Make sure each group has counted the number of sheets of paper used in their final tower design. Sheets used in earlier prototypes do not count. Record this value on the Student Worksheet.
2. One at a time, while the whole class watches, place a can of food on top of the tower and start the stopwatch.
3. Make sure the tower holds the can for  minute without collapsing. It is okay if the tower begins to sag or buckle, as long as the can does not touch the ground. Students are not allowed to touch, repair, or modify the tower during this minute.
4. After 1 minute has elapsed, use a tape measure or meterstick to measure the distance (in centimeters) from the supporting surface (floor, tabletop, etc.) to the bottom of the can. If necessary, you are allowed to use your hands to stabilize the tower or the can when taking your measurement, but do not lift the can to a higher height (this helps ensure that you do not accidentally knock the can over with the tape measure or meterstick—that would be frustrating!). Record this height on the Student Worksheet.
5. Each group can calculate their score using the equation on the Student Worksheet.

Discuss the results of the competition as a class.

• What structural elements seemed to work the best? Did all groups reach the same conclusion?
• What engineering tradeoffs did groups make in their designs?
• What challenges did groups encounter and how did they address them?

Assess

• Collect your students' worksheets and use them to assess how they worked through the design process.
• Ask each group to do an oral presentation about their design, including the engineering challenges they faced and how they addressed them.

Make Career Connections

Discussing or reading about these careers can help students make important connections between the in-class lesson and STEM job opportunities in the real world.

Civil Engineers

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Career Profile

Civil engineers design and supervise the construction of buildings, dams, bridges, highways and other major public works. Within civil engineering there are several subspecialties including structural engineering. Structural engineers are responsible for making sure a building is stable and can bear the forces that will act on it. While designing and building your paper tower, you acted like a structural engineer by working to create a tower that could successfully support a large load —a can of food. Read more

Engineering Manager

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Career Profile

Designing and constructing buildings requires deep collaboration between many engineers and technical workers. Engineering managers work to ensure that team members from all disciplines are communicating effectively and that the project is moving along at a good pace. Engineering managers also step up to lead the problem-solving process when unexpected hurdles or setbacks are encountered. If you worked in a team on this paper tower challenge, did anyone on your team fill the role of an engineering manager? Read more

Lesson Plan Variations

Did your students enjoy this type of hands-on project? Check out the other Engineering Challenges and try them in your classroom!