Hands-on Activity: Maximum Mentos Fountain

Contributed by: RESOURCE GK-12 Program, College of Engineering, University of California Davis

A photograph shows four Mentos geysers of different heights going off at the same time in front of a garage door. Each contains five plain Mentos drops, but different liquids. Left to right: carbonated water (Perrier), Classic Coke, Sprite and Diet Coke. Green marks on the garage door indicate 0.5 m height marks. The Diet Coke shoots the highest, then the Classic Coke, then Sprite, then carbonated water.
Students build Mentos fountains
Copyright © 2007 K. Shimada Wikimedia Commons http://commons.wikimedia.org/wiki/File:ShimadaK2007Sept09-MentosGeyser_DSC_3294%2B%2B.JPG


Students play the role of engineers as they test, design and build Mentos® fountains—a dramatic example of how potential energy (stored energy) can be converted to kinetic energy (motion). They are challenged to work together as a class to optimize the design of the basic soda/candy geyser made by the teacher. To do this, three research teams each investigate how a different variable—nozzle shape, soda temperature, number of candies—affects fountain height. They devise and run experimental tests to determine the best variable values. Then they combine their results to design the highest fountain to compete head-to-head with the teacher's geyser design.

Engineering Connection

Through this activity, students gain experience with two tasks that are vital to many real world engineering projects: 1) systematically testing, evaluating and optimizing a design, and 2) collaborating with other engineers or research groups.

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.

Suggest an alignment not listed above

Learning Objectives

After this activity, students should be able to:

  • Explain the difference between kinetic and potential energy.
  • Collect and interpret experimental data.
  • Collaborate with other groups.
  • Revise a design based on test results.

Materials List

Each group needs:

For the entire class to share:

  • capability to show an online video


Today I have a design challenge for you. You are going to work together as a class to optimize the design of a Mentos® fountain. Before we get started let's watch a video.

(Show students the following two-minute video explaining the science behind Mentos® fountains: http://www.discovery.com/tv-shows/mythbusters/videos/diet-coke-and-mentos-minimyth.htm.)

Now we know how Mentos® fountains work. Who can explain the process in terms of energy? Use the terms potential energy, kinetic energy and energy transfer in your explanations. (At a minimum, expect students to be able to explain that the process is an energy transfer from potential energy to kinetic energy and that the movement of the soda is how we can tell that kinetic energy is present. In addition, students may also be able to identify that the energy is originally stored in the carbonation as chemical potential energy. Further, students may also be able to explain that as the soda goes up, its kinetic energy is transferred to gravitational potential energy, which converts back to kinetic energy as the soda falls back down.)

Great! Now I'm handing out the worksheet for our activity so we can get started.


energy: The ability to make things happen. More advanced definition: The ability to do work.

energy conversion: The change of energy from one form to another.

kinetic energy: The energy of moving objects. Anything in motion has kinetic energy. The faster an object moves, the more kinetic energy it has.

optimize: To balance many (often competing) requirements to achieve the best design for the circumstances.

potential energy: Energy that is stored and can be used when needed. Energy can be stored in chemicals (food, batteries), height (gravitational), elastic stretching, etc.


Before the Activity

With the Students

  1. Present the Introduction/Motivation content to the class, including showing the MythBusters' video explaining the science behind the soda/candies geysers.
  2. Divide the class into three research groups and hand out the worksheets.
  3. Explain that you have designed a Mentos® fountain, and that the design challenge for the class is to design a Mentos® fountain that will go higher than yours. Your design uses an x-shaped nozzle, room temperature soda, and 5 Mentos® candies (as indicated on the worksheet). This design is the baseline for the class optimization effort.
  4. Assign a different variable to each group. The variable choices, as listed on the worksheet, are nozzle shape, soda temperature (room temperature vs. cold), and number of Mentos® candies. Other variables could be used, such as soda type.
  5. Explain that each research group is responsible to determine the best value for its variable. They are to run several tests using different values for the variable, while all other variables match the base design.
  6. Direct the groups to work together to make a plan, guided by the worksheet, completing the worksheet up to the results column in the big table.
  7. Outside, have the research groups carry out the tests they have designed and record the results. The results may be descriptive ("about as high as a classroom, higher than run 1, least high of all," height compared to some landmark like a flagpole or playground equipment, etc.) or use a height-o-meter to measure the height. Tips: Set off only one fountain at a time. Carefully inspect the fountain before pulling the pin to make sure everything is set up correctly.
  8. After testing is completed, have each research team confer to determine the best option for the variable they tested.
  9. Next, direct all three research groups to get together and decide what final fountain design they think will go the highest. Tips: More Mentos® are better than fewer. Room temperature soda is better than cold.
  10. Do a side-by-side test with the Mentos® fountain you designed (the baseline design on the worksheet) and the fountain design based on the collaborative class research. If the student experiments went well, expect their fountain to be higher.
  11. Conclude by leading a class discussion, as described in the Assessment section. Also have students complete and turn in their worksheets.


Troubleshooting Tips

This activity is messy so conduct it outside in a location that can be easily washed afterwards.

For safety, make sure students stand back when triggering Mentos® fountains.


Pre-Activity Assessment

Review Questions: Have students answer the two fill-in-the-blank review questions at the top of the Mentos Fountain Worksheet. The answers are: 1) potential, chemical, or chemical potential, and 2) kinetic.

Activity Embedded Assessment

Observations: While students are working in their research teams, observe how they plan and carry out the experiments. Notice their logic, how they interpret their results and how they collaborate with the other groups. Ask students how they chose their test cases and what they concluded from their results. Review their Mentos Fountain Worksheets for thoroughness and accuracy.

Post-Activity Assessment

Project Reflection: As a class, review and discuss the activity. Pay particular attention to the process and reasoning that students followed to determine the class' final fountain design. This process is similar to the scientific method and to engineering design practices. Discuss whether their predictions were correct or incorrect and why. Discuss anything students observed that surprised them.

Worksheets: Collect students' completed Mentos Fountain Worksheets. Examine them to see if they followed the process outlined on the worksheet and collected reasonable and accurate data.


Report: Assign students to individually write short reports about the activity. Require them to explain how a Mentos® fountain works in terms of energy and describe the design optimization process they went through to achieve the maximum height geyser.


Eric Anderson, Jeff Kessler, Irene Zhao


© 2014 by Regents of the University of Colorado; original © 2013 University of California Davis

Supporting Program

RESOURCE GK-12 Program, College of Engineering, University of California Davis


The contents of this digital library curriculum were developed by the Renewable Energy Systems Opportunity for Unified Research Collaboration and Education (RESOURCE) project in the College of Engineering under National Science Foundation GK-12 grant no. DGE 0948021. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.