Educator Features

Pressure and Bendability
Teacher Section

Objective: To observe how an external joint increases the bendability of a space suit arm segment.

Grade Level: 5-8
Subject(s): Science
Prep Time: < 10 minutes
Duration: 50 minutes
Materials Category: Special

National Education Standards
Science as Inquiry
        Abilities necessary to do scientific inquiry
Physical Science
        Properties and changes of properties in matter
Life Science
Science and Technology
  • Long balloons
  • Heavy-duty rubber bands
  • Slinky® (optional)
  • Student Page
Pre-lesson Instructions
  • Students should work in groups of two to four for this lesson.
Background Information

Maintaining proper pressure inside a space suit is essential to astronaut survival during a spacewalk. A lack of pressure will cause body fluids to turn into gas, resulting in death in a few seconds. While making spacewalks possible, pressure produces its own problems. An inflated space suit can be very difficult to bend. In essence, a space suit is a balloon with an astronaut inside. The rubber of the balloon keeps in oxygen that is delivered to the suit from pressurized oxygen tanks in the backpack. But, as pressure inside the balloon builds, its walls stiffen, making normal bending motions impossible. Lack of flexibility defeats the purpose of the space suit: mobility and the ability to do work in space.

Space suit designers have learned that strategically placed breaking points at appropriate locations outside the pressure bladder (the balloon-like layer inside a space suit) make the suit more bendable. The breaking points help form joints that bend more easily than unjointed materials. In the restraint layer, stitching folds spread apart and contract to aid bendability. Joints are also built into this layer, serving like ribs on a dryer vent hose to make the layer easier to bend.


  1. As a class, discuss spacewalking and why astronauts need space suits. Space suits provide protection from micrometeorites, radiation and extreme temperatures. They also provide oxygen and keep the astronaut in a pressurized environment.

  2. Discuss the information found in the Background Information. Talk about the difficulties of working in a pressurized suit. Discuss the idea of a space suit being similar to a balloon.
    Astronaut on a spacewalk with the Earth as a backdrop

  3. Explain that the class is going to be completing an activity to better understand the difficulty of working in a pressurized suit.
Image to right: Space suits protect astronauts during spacewalks. Credit: NASA

  1. Divide the students into groups and distribute the Student Page.

  2. Go over the activity directions as a class. Answer any questions the students might have.

  3. Distribute materials and allow time for students to complete the activity.

  • Encourage classroom discussions based on the results of the groups' activities.
  • Optional demonstration: use a Slinky® as an alternative to the rubber bands. Place the Slinky® on a desktop and pick up one end. Slip in the balloon, and inflate it. As the balloon inflates, it will be pinched in a spiral pattern by the Slinky®. The pattern will achieve the same results as the rubber bands.

Slinky® is a registered trademark of Poof-Slinky, Inc.

Pressure and Bendability Student Page