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Cups Under Pressure

Grades: 4-6
Author: Anthony Crane, Mindy Marker, Jenn Stormer, Joe Johnston, AGPA Staff
Source: Steve Spangler Science -


Students will observe how a Styrofoam cup shrinks under pressure in a cooker.


What should students know as a result of this lesson?

  • Students will know what a pressure cooker does
  • Students will know uses for Styrofoam
  • Students will know what polymers are
  • Students will know difference between physical and chemical changes

What should the students be able to do as a result of this lesson?

  • Students will be able to write a hypothesis, collect data, draw conclusions, and report results from an experiment
  • Students will be able to compare/contrast an item before and after an experiment
  • Students will be able to calculate percentage


  • Styrofoam packing peanuts
  • Styrofoam cups
  • Permanent markers
  • Rulers
  • Pressure cooker
  • Ceramic dish that fits inside pressure cooker
  • Water



  • Give each student a Styrofoam packing peanut.
  • Let the students manipulate the packing peanuts while having a discussion about the properties of the item.

Assessment: Monitor that the students are making observations about the material's properties.


  1. Students will decorate a cup using permanent markers to put into the pressure cooker.
  2. Before placing the cup into the pressure cooker
    1. Each student will write a hypothesis about what will happen to the cup after it is in the pressure cooker
    2. Each student will measure the dimensions of the cup (diameter of opening, height)
    3. Each student will make observations
  3. After the procedure
    1. Each student will measure the dimensions of the cup
    2. Each student will make observations
  4. Students will analyze results from the experiment
    1. Students can calculate the percentage that the cup shrank

Assessment: Monitor that the students are staying on task, using proper procedures, and recording the necessary data.


  1. As a class, discuss the results of the experiment and conclusions.
  2. Discuss the hypotheses the students wrote and discuss if the results were expected
    1. Explain to the students that more information is learned if the results are not what was expected
  3. Explain that Styrofoam is actually a polymer called polystyrene
    1. To make the Styrofoam, the polystyrene has been expanded and the final product consists primarily of air
    2. The air inside the polymer creates a very good insulating material, which is why Styrofoam cups are good for hot beverages
    3. In the pressure cooker, a large amount of the air has been removed and the cup is compressed
  4. Explain that the change that occurred in the cup is a physical change and not a chemical change (see Content Knowledge)
  5. Explain what a pressure cooker is (see Content Knowledge)
  6. Introduce polymers (see Content Knowledge)

Assessment: Monitor that students are participating in the discussion and understanding the concepts presented.


  1. Have groups of 4 students investigate one of the following topics:
    1. Determine other uses of Styrofoam (keeping items cold, keeping items protected during shipping) and research current environmental concerns about Styrofoam
    2. Compare polymers as insulators with the material classes of ceramics and metals and determine advantages/disadvantages of the various materials

Assessment: Students can write a short report on their findings or the students (as a group) can present their findings to the class.


Basic math skills are necessary for the calculations.

Best Teaching Practices

  • Graphic Organizer
  • Hands-on/Minds-on Learning
  • Learning Cycle

Alignment with Standards

NGSS Standards:

  • 5-PS1-2 Measure and graph quantities to provide evidence that regardless of the type of the change that occurs when heating, cooling, or mixing substances, the total weight of matter is conserved.
  • MS-PS1-3 Gather and make sense of information to describe that synthetic materials come from natural resources and impact society.

Common Core Standards:

  • RST.6-8.3 Follow precisely a multistep procedure when carrying our experiments, taking measurements, or performing technical tasks.
  • WHST.6-8.2 Write informative/explanatory texts, including the narration of historical events, scientific procedures/experiments, or technical processes.

National Standards:

  • Physical Science Grades K-4, 5-8
  • Science as Inquiry Grades K-4, 5-8

Ohio Standards:

  • Grades 3-5: Physical Science Benchmark B
  • Grades 3-5: Scientific Inquiry Benchmarks A & B
  • Grades 6-8: Scientific Inquiry Benchmark B
  • Grades 6-8: Physical Science Benchmark A

Content Knowledge

Information on the specific experiment and pressure cookers can be found at

Polymers are long chain molecules that are naturally occurring and man-made (synthetic). They are present in many different forms in our everyday world.

See the AGPA website for polymer information. Specifically, the narrated PowerPoint presentation at has basic polymer information.

Another useful website is the Macrogalleria

Information on chemical changes and physical changes can be found at

Basic information on the classes of materials can be found at


Pressure cookers can be potentially very dangerous. Read the manufacturer's instructions and follow them carefully. Mainly, the pressure needs to equalize before opening the vessel.

Students should wear safety goggles.

General science classroom safety should be followed.


Polymers have become a major part of our everyday lives. Metals, ceramics, and composites are the other classes of materials and understanding a material's properties is important.


Students should summarize the experiment in a paragraph.

Measurements/calculations among the class will be compared.

Other Considerations

Grouping Suggestions Groups of 4. Each student collects own data.

Pacing/Suggested Time: This lesson can be an hour lesson or more in-depth as a culminating experiment after a weeklong unit on polymers.

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