Hands-on Activity: A Simple Solution for the Circus

Contributed by: Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder

The Howard Bros. Circus in Sarasota, FL.
Students devise a solution for the circus
Copyright © Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/c/c1/Howard_Bros.Circus.JPG


In this activity, students are challenged to design a contraption using simple machines to move a circus elephant into a rail car. After students consider their audience and constraints, they work in groups to brainstorm ideas and select one concept to communicate to the class.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering Connection

Many mechanical devices designed by engineers have simple machines embedded in their structure, including elevators, escalators, construction equipment, and even medical devices. The same physical principles and mechanical advantages of simple machines used by ancient engineers to build pyramids are employed by today's engineers to construct modern structures such as houses, bridges and skyscrapers.

Pre-Req Knowledge

The students need to be familiar with the six simple machines (at least by name), found in the associated Simple Machines Lesson 1 "The Advantage of Machines."

Learning Objectives

After this activity, students should be able to:

  • Recognize and identify the six simple machines.
  • Define the concept of work.
  • Explain why engineers are interested in simple machines.

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Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Predict and evaluate the movement of an object by examining the forces applied to it (Grade 8) Details... View more aligned curriculum... Do you agree with this alignment?
Suggest an alignment not listed above

Materials List

Each group needs:

  • Pencil, with eraser
  • Ruler
  • Colored pencil or marker (optional)
  • 1-2 piece of white paper (can be used on one side)
  • Copy of the Simple Solution Instructions


Today we are going to design a device to lift a heavy object —an elephant. Following is the scenario: the Big Top circus travels from town to town by rail. On its way to your town, the circus train jumped track, and the rail car with the elephant inside tumbled over. Local rail line workers were able to get the train back on track, but the circus still has a problem: the elephant is not inside the rail car. How do you suppose they can get the elephant back into the rail car? Your task as engineers is to move the elephant the six feet from the ground to the rail car (and therefore, successfully into the car!). The circus has very limited money for supplies, and you must design your process so the circus can get to your town by nightfall for their performance.

Engineers are often asked to solve design challenges such as this one. The first step in designing a proper solution is to recognize the need. Who is your customer that you need to make happy? Well, the circus administration is certainly one, since they are hiring you. Can anyone think of another customer? Of course, the elephant! You need to make sure the elephant is happy, and not injured, during the process you design to get him back onto the train.

Next, an engineer has to define the problem that she is working on for her clients (in this case, the circus company). The problem needs to be well-thought out, but does not limit the solutions. What is one way that we could phrase this problem with the elephant? Well, we could say, "Design a device to lift an elephant onto a train." That would be okay, but maybe, "Get elephant onto the train" might be a better problem statement, because we have already limited the problem in the first statement by saying "lift" the elephant onto the train.

Then, an engineer needs to think about the design requirements and constraints (limitations) for the problem. Can anyone think of some design requirements or constraints for our problem? (Possible answers include: limited money for materials, limited time since we need to do this fast, and the device or process needs to be safe for the elephant.) We have another unique requirement for this particular task, however, and that is we need to use at least one simple machine in our design.

Next, we think about information that might help us solve the problem at hand. We know that designing a mechanical device to lift heavy objects is a classic example of engineering. And, it turns out that most mechanical devices for doing physical tasks — such as lifting elephants — are composed of simple machines, which we are required to use in our design for this activity. So, let's review. What is a simple machine? (Answer: A device, or several combined devices, that make work easier.) What are the six simple machines? (Answer: inclined plane, screw, wedge, lever, wheel-and-axle, pulley) Let's quickly refresh our memories on what they all look like, since you might include one or more of them in your design. Take out a piece of paper and work with the person sitting next to you to draw all six simple machines.

Now, we are ready to brainstorm ideas for our design. We want to encourage many ideas in our design, and all ideas should be respectfully heard and recorded. In a good engineering brainstorming session, we remain focused on one topic and build on the ideas of others. Let's remember our project (activity) requirements and constraints: limited money for materials, limited time, safe for the elephant and we need to use at least one simple machine in our design.


Before the Activity

  • Make enough copies of the Simple Solution Instructions so that each group of students has one copy.

With the Students

  1. Arrange students into groups of 3.
  2. Distribute copies of the Simple Solution Instructions.
  3. Give the groups 5 minutes to brainstorm ideas and discuss which idea they think is their most promising.

Note: There is no material constraint except for a limited budget; however, it is important that the device is made out of appropriate materials for the task. For example, the material that wraps around the elephant to pick it up should not be tissue paper since it is not nearly strong enough nor should it be made of titanium, since that is too expensive.

  1. Give students 10 minutes to make a drawing on white paper that illustrates the device and explains how it will work.

Note: This can be highly creative. Try to help students think through the problem using simple machines. For example, try to avoid electronics. Instead of a button you push to raise the device's arm, there might be a hand crank (wheel-and-axle).

  1. Have each group present their invention for one minute, describing how it works and how it is put together.
  2. After each group has presented, ask the class to identify some common solutions to the problem. Which were the most expensive designs? Were the less expensive designs feasible? How did the designs demonstrate the safety for the elephant? Why is the elephant's safety important to the circus?



Pre-Activity Assessment

Discussion Question: Solicit, integrate and summarize student responses.

  • What are the six simple machines? (Answer: inclined plane, screw, wedge, lever, wheel-and-axle, pulley)

Design Requirements and Constraints: Have the students make a list on the board of the problem's design requirements and constraints. Some examples might include: limited money for materials, limited time, safety for the elephant, and using at least one simple machine in the design.

Activity Embedded Assessment

Worksheet/Engineering Design: Have the students complete the activity worksheet. Review their inventions to gauge their mastery of the subject.

Post-Activity Assessment

Design Presentation: Engineers need to be able to communicate their ideas effectively to their audience. Have each group present their design and drawing to the rest of the class for one minute describing how it works and how it is put together. Discuss the design. Is it feasible? Were all of the requirements and constraints met (limited money for materials, limited time, safety for the elephant, and using at least one simple machine in the design)?

Class Discussion: Have the student think about their designs. Were there competing factors that influenced their designs? For example, did the limited money for material or limited time affect their design? What might they have changed with more time or money? Did their design have an impact on the environment? Did they consider the safety of the rail workers as well as the elephant in their design? Are the rail workers a customer as well, even though they do not work for the circus?

Activity Extensions

Have students think about some of the questions posed in the Post-Activity Assessment as a class discussion. Instruct them to write a short paper discussing some of the impacts of their design on the various audiences involved, including the elephant, the circus workers, the rail workers, the environment, the people waiting for the circus to come to town, etc.

Have each group think of another situation where simple machines could be used to make a task easier. Ask them to write their ideas down on a piece of paper. The groups should then exchange slips of paper and solve the presented problem incorporating the use of simple machines.


Melissa Straten; Glen Sirakavit; Michael Bendewald; Malinda Schaefer Zarske; Janet Yowell


© 2007 by Regents of the University of Colorado.

Supporting Program

Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder


The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and National Science Foundation GK-12 grant no 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: August 10, 2017