The Arizona STEM Acceleration Project

Balanced Forces: Tensegrity structure

Illusion of Balance:

Crafting Tensegrity Marvels

A 9th-12th grade STEM lesson

Freddy Melara

1/28/2024

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Notes for teachers

This lesson will take about 90-120 minutes.

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Students should work in groups of 2-4 with the expectation that larger groups will have added difficulty in their construction.

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The objective will be the create the structure and have a weight requirement.

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There will be a functionality requirement, meaning that students must document how they can integrate their structure in real life (e.g. use as a seat, plant holder, etc.)

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List of Materials

• Popsicle sticks or wooden dowels
• Hot glue
• String
• Paint
• Scissors
• engineering design process document

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AZ High School Standards

Physical Science:

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HS.P3U2.7 Use mathematics and computational thinking to explain how Newton’s laws are used in engineering and technologies to create products to serve human ends.

*Interactions between any two objects can cause changes in one or both of them. An understanding of the forces between objects is important for describing how their motions change, as well as for predicting stability or instability in systems at any scale.

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Technology:

9-12.3.a. Students plan and employ effective research strategies to locate information and other resources for their intellectual and/or creative pursuits.

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Core Ideas for Using Science:

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U2: The knowledge produced by science is used in engineering and technologies to solve problems and/or create products.

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Science & Engineering Practices:

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● ask questions and define problems

● develop and use models

● plan and carry out investigations

● analyze and interpret data

● use mathematics and computational thinking ● construct explanations and design solutions

● engage in argument from evidence

● obtain, evaluate, and communicate information

Objectives:

• Today we will explore how forces are balanced in a tensegrity structure. We'll look at why it doesn't fall apart by understanding how push and pull forces work together.
• Today we will collaborate and communicate effectively with our peers to complete an engineering design challenge.

Agenda (90-120 minutes)

What is a tensegrity structure?

What contact forces do we usually see when it comes to structures built in real life?

Can we achieve the same result using forces that “push” vs forces that “pull”?

Test for build requirements.

What is a tensegrity structure?

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A tensegrity structure is a fascinating architectural and structural design principle that involves a system of isolated components under compression inside a network of continuous tension, in such a way that the compressed members (usually bars or struts) do not touch each other and the pre-stressed tensioned members (usually cables or tendons) delineate the system spatially.

It is a system that uses tension forces instead of support forces to hold a structure. In layman’s terms: we use pull forces instead of push forces to accomplish the same result.

Image by Giovanni Pilon

Hands-on Activity Instructions

• Two to four students per group (there should be a minimum support requirement). E.g. must hold 1 kg, etc.
• Students should read through Engineering Design Process Document before any construction can start.
• There should be evidence of brainstorming (sketches, videos, articles, FORCE DIAGRAM etc.) No construction should take place on the first day so that students can think of their project without rushing to just build.
• Prototype should be built and then repeatedly tested.
• Final product should be able to hold weight requirement AND must be shown in a real world application (e.g. how the project can be used in a real context)

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How do we assess our project?

• Can it withstand the weight requirement? (Will vary depending on group size).
• Is there a trail of evidence that suggests there was authentic collaboration and brainstorming to come up with final design?
• Evidence of the project used in real life.

Differentiation

• Some students struggle with continuously improving their project. Having a basic design for student to follow to show minimum proficiency is helpful for students who struggle to be engaged. This might look like a basic design from the internet or a YT video.
• “Kits” with the materials can be premade for students who are absent. This is a project that can be worked on outside of class without too much guidance.
• Engineering Design Workshop: the document/presentation portion of the activity is something students struggle with. Having a workshop for students who struggle can be help for getting them started and showing guidance.

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Remediation

Extension/Enrichment

“We can always use more seating/decor in the class”

This is my way of challenging students to create something that can be used in the class. I like to call these challenges “legacy” projects

“Most original/creative design”

This is my way of having students try to be as authentic as possible with their project.

“Is there a way to create a “true” floating structure using field forces?”

This is my way of having students think of how magnets can potentially be used as another means to support a structure.