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Geyser Geeks: Discovering Yellowstone's Epic Eruptions

Updated: Oct 19, 2023

Objective: In this lesson, students will explore the formation and eruption of geysers in Yellowstone National Park. They will define geysers, identify the necessary ingredients for geyser formation, and create model geysers to simulate eruptions.

Grade Level: Middle School (6th - 8th Grade)

Duration: 2 class periods

Materials Needed:

  • Antacid seltzer tablets (halves)

  • Plastic film canisters with lids

  • Needle or safety pin

  • Warm water

  • Geyser Worksheet and Observation Guide (printable)

  • Vinegar

  • Baking soda

  • Soda bottles

  • Clay

  • Straws

  • Plastic cups

  • Plastic bowls

  • Funnels

  • Paper

  • Pencil

  • Geyser Assessment Rubric (for teacher assessment)

Lesson 1: Understanding Geysers (45 minutes)

Step 1: Introduction (10 minutes)

  • Begin by discussing the uniqueness of Yellowstone National Park and its famous geysers.

  • Explain to students that they will learn about the ingredients required for a geyser to exist and the process of geyser eruption.

Step 2: Defining and Identifying Ingredients (15 minutes)

  • Have students write a definition of a geyser in their notebooks.

  • Discuss the three key ingredients necessary for a geyser: a source of heat, an abundant supply of water, and a special underground plumbing system.

  • Ask students to list these ingredients on the Geyser Worksheet and Observation Guide.

Step 3: Geyser Demonstration (20 minutes)

  • Conduct a simple geyser demonstration to illustrate the eruption process.

  • Make a small hole in the lid of a plastic film canister using a needle or safety pin.

  • Select a student to assist with the demonstration.

  • Fill the film canister ¾ full with warm water.

  • Instruct the student to add half of an antacid seltzer tablet to the canister.

  • The student should quickly replace the lid and place a finger over the hole in the lid.

  • Instruct the student to shake the canister a few times and then remove their finger from the hole.

  • Ask the class to observe the ensuing eruption.

  • Discuss what happened and why it occurred.

Homework: Ask students to research and find a real geyser in Yellowstone National Park and write a brief description of its characteristics.

Lesson 2: Building and Testing Geyser Models (45 minutes)

Step 1: Review (10 minutes)

  • Recap the key ingredients for geyser formation and the demonstration from the previous lesson.

Step 2: Geyser Model Activity (25 minutes)

  • Divide the students into small groups of 3-4.

  • Provide each group with materials to create their own geyser model (e.g., soda bottles, clay, straws, plastic cups, etc.).

  • Instruct students to assemble their geyser models and simulate eruptions using baking soda and vinegar.

  • After the activity, each group should explain why they assembled their geyser models in a particular manner.

Step 3: Hypotheses and Evaluation (10 minutes)

  • Ask students to write down their hypotheses about which geyser model most accurately represents a real geyser.

  • Discuss the concept of heat creating pressure in the Earth and the chemical reaction of baking soda and vinegar as a representation of pressure.

Homework (optional): Assign students to write a short reflection on what they learned about geyser formation and how they can relate it to real geysers in Yellowstone.

Assessment: Use the Geyser Assessment Rubric to evaluate students' understanding of geyser formation and the quality of their geyser models.


  • Lead a group discussion or have students predict how various factors (e.g., earthquakes, drought, volcanic eruptions, geothermal energy drilling, human interference) might affect the behavior of geysers in Yellowstone.

  • Engage students in a debate about whether geysers in Yellowstone should be preserved in their natural state or used for energy production.

For more information or to take a school group to Yellowstone contact Appleseed Expeditions at

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