Hands-on Activity: The Squeeze Is On

Contributed by: Center for Engineering Educational Outreach, Tufts University

An array of bricks stacked on top of eachother.
Students examine the force of compression and how it acts on structural components
copyright
Copyright © Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/2/27/A_brick_array.JPG

Summary

Through hands-on group projects, students learn about the force of compression and how it acts on structural components. Using everyday materials, such as paper, toothpicks and tape, they construct structures designed to (hopefully) support the weight of a cinder block for 30 seconds.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering Connection

When civil engineers are asked to design a building, one thing they must calculate is the total compressive load that will be at work in the structure. To do this, they take into account the anticipated loads resulting from how people will use the building and the weight of the structure itself. Based on these calculations, materials with appropriate properties for carrying the weight are chosen, and structural components (such as columns and beams) are designed to provide adequate support and weight distribution.

Learning Objectives

  • Students gain insight into structural supports designed to withstand compression.
  • Students develop construction skills.
  • Students learn about the fundamental loads.

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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.

  • Develop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Requirements for design are made up of criteria and constraints. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Brainstorming is a group problem-solving design process in which each person in the group presents his or her ideas in an open forum. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Modeling, testing, evaluating, and modifying are used to transform ideas into practical solutions. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Specify criteria and constraints for the design. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Make two-dimensional and three-dimensional representations of the designed solution. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Test and evaluate the design in relation to pre-established requirements, such as criteria and constraints, and refine as needed. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • The selection of designs for structures is based on factors such as building laws and codes, style, convenience, cost, climate, and function. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Buildings generally contain a variety of subsystems. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Explain how the forces of tension, compression, torsion, bending, and shear affect the performance of bridges. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Demonstrate methods of representing solutions to a design problem, e.g., sketches, orthographic projections, multiview drawings. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Identify appropriate materials, tools, and machines needed to construct a prototype of a given engineering design. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Explain how such design features as size, shape, weight, function, and cost limitations would affect the construction of a given prototype. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
Suggest an alignment not listed above

Materials List

  • cinder blocks to use as weights (or a stack of uniform textbooks)

Each group needs:

  • piece of wood (a smooth flat object to put the cinder blocks on)
  • 4 3" x 5" index cards
  • 8.5" x 11" copier paper
  • 8.5" x 11" plastic transparency
  • 12" masking tape
  • (optional) 15 toothpicks
  • (optional) 2 drinking straws
  • ruler
  • scissors
  • 4 pairs safety glasses

Introduction/Motivation

Name some "strong" materials. (Listen to student ideas. Write them on the board. Expect students to suggest steel, concrete, wood, etc.)

Would you believe that a piece of paper, used creatively, could support the full weight of a cinder block?

Vocabulary/Definitions

compression: Two pushing forces, directly opposing each other, that squeeze an object and try to squash it. For example, standing on an aluminum can, squeezing a piece of wood in a vise; both the can and the wood are in compression or are "being subjected to a compressive load."

force: A pushing or pulling action that moves, or tries to move, an object.

internal stress: An internal force that develops inside materials that resists outside forces and fights to hold a structure together.

load: External forces that are acting on a structure.

structure: An object that can hold up weight and withstand forces that are placed on it. Examples: buildings, bridges, dams, planes, car chassis, bicycle frames.

Procedure

Before the Activity

  • Conduct the "Introduction to Loads on Structures" activity to help increase what the students will be able to understand from doing the activity.
  • Gather materials.
  • Set-up a safe test area.

With the Students

  1. Divide the class into groups of three or four students each.
  2. Your team's engineering challenge: Using the material provided, design and build a structure or structures that is able to hold a concrete cinder block at a height of 3 inches above the floor for 30 seconds. Then, more cinder blocks will be added until the structure fails.
    Photo shows two structures made of paper, plastic, straws and tape.
    Figure 1. Example structures.
    copyright
    Copyright © 2005 Center for Engineering Educational Outreach, Tufts University
  3. Give groups 10 minutes to brainstorm, during which time students sketch their design ideas. When the time is up, pass out the materials. Indicate that the maximum amount of time permitted to build the structure is 15 minutes.
  4. Test the structures in the test area. Require students in the test area to wear safety glasses. Have each team place its structure(s) on the floor and position the board onto the structure. Once it is in place, have two team members slowly and carefully lower a cinder block onto the board. Advise students to place the block as evenly as possible onto the board in order to avoid creating any twisting forces. Direct the team members who are not moving the block to carefully watch the structure to see where and how it fails. After 30 seconds, the structure is deemed successful. Add more weight until failure. Record how much weight the structures supported before failure. !!Warning!! Watch out for fingers and feet during testing!

Safety Issues

During testing, have students wear safety glasses in the test area. Also watch for fingers and feet when adding weight!

Investigating Questions

  • What is compression and what effect does it have on structures (structural elements)?
  • Give examples of compression and find real life examples of structural elements that are in compression.
  • How did your structure fail?
  • Did it twist or slide to one side as it collapsed? If so, what do you think caused your structure to fail this way?

Assessment

Copyright

© 2013 by Regents of the University of Colorado; original © 2005 Worcester Polytechnic Institute

Supporting Program

Center for Engineering Educational Outreach, Tufts University

Last modified: March 10, 2018

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