Science · Grade 7

Active learning ideas

Tension and Compression in Structures

Active learning works because tension and compression are invisible forces that students must experience to truly understand. By building and testing models, students see how forces shape structures in real time, turning abstract concepts into concrete evidence they can explain and improve.

• Ontario Curriculum Expectations
• MS-ETS1-2

• 40–60 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Experiential Learning
• 45 min · Small Groups

Model Building: Bookshelf Analysis

Provide popsicle sticks, glue, and books as weights. Students assemble a simple bookshelf model, then mark tension and compression zones with colored tape. Load the model gradually and discuss observed changes.

Explain where the tension and compression are located in a simple wooden bookshelf.

Facilitation Tip

During Model Building: Bookshelf Analysis, circulate to ask guiding questions like, 'How does the shelf’s weight affect the supports? What happens if you add more books?' to push students toward causal reasoning.

What to look for

Present students with images of different structures (e.g., a simple stool, a tent, a flagpole). Ask them to label areas of tension and compression on each image and briefly explain their reasoning.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 02

• Experiential Learning
• 50 min · Pairs

Bridge Challenge: Suspension Design

Use string, straws, and tape to build a mini suspension bridge spanning two desks. Students predict force distributions, test with weights at center, and adjust based on failures. Record before-and-after sketches.

Analyze how tension and compression work together in a suspension bridge.

Facilitation Tip

During Bridge Challenge: Suspension Design, remind students to measure and record the deflection of their bridge under load before making adjustments.

What to look for

Provide students with a diagram of a simple wooden bookshelf. Ask them to identify one part experiencing compression and one part experiencing tension, and write one sentence explaining why.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 03

• Experiential Learning
• 40 min · Small Groups

Force Testing Stations

Set up stations with truss models, rubber bands for tension, and stacked blocks for compression. Groups rotate, apply loads, measure deformation with rulers, and compare results in a class chart.

Design a simple structure that primarily uses tension to support a load.

Facilitation Tip

During Force Testing Stations, assign each group a different station first and rotate them through all three to ensure equal exposure to varied examples.

What to look for

Pose the question: 'How do the forces of tension and compression work together in a suspension bridge to keep it stable?' Facilitate a class discussion where students share their ideas and build upon each other's explanations.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

Activity 04

• Experiential Learning
• 60 min · Small Groups

Design Lab: Tension-Dominant Structure

Challenge students to design a structure supporting maximum load using mostly tension, like a hanging hammock frame. Build prototypes, test iteratively, and present force analyses.

Explain where the tension and compression are located in a simple wooden bookshelf.

Facilitation Tip

During Design Lab: Tension-Dominant Structure, provide a limited set of materials (e.g., straws, string, tape) to focus the challenge and make trade-offs visible.

What to look for

Present students with images of different structures (e.g., a simple stool, a tent, a flagpole). Ask them to label areas of tension and compression on each image and briefly explain their reasoning.

• Apply
• Analyze
• Evaluate
• Self-Awareness
• Self-Management
• Social Awareness

A few notes on teaching this unit

Approach this topic by starting with familiar objects students can relate to, then layering in technical language and testing protocols. Avoid rushing to definitions; instead, let students articulate their own ideas first, then refine them through structured investigations. Research shows that iterative testing and discussion help students reconcile misconceptions about force distribution and failure patterns.

Successful learning looks like students using precise vocabulary to describe forces, predicting how changes in design will shift tension or compression, and revising their structures based on evidence from testing. They should move from casual observations to technical explanations that link form and function.

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Watch Out for These Misconceptions

• During Model Building: Bookshelf Analysis, watch for students who assume the entire bookshelf experiences the same force.

  Use the bookshelf model to point out how the shelf itself compresses under weight while the vertical supports tense to hold it up. Have students mark these zones on their models with colored pencils and explain the difference to their peers.

• During Bridge Challenge: Suspension Design, watch for students who believe tension and compression act separately in the bridge.

  After testing, gather the class to examine the bridge’s failure points. Ask students to trace how the cables (tension) pull upward while the towers (compression) push downward, then sketch the force paths on the board together.

• During Force Testing Stations, watch for students who think structures fail only when overloaded, not because of poor force distribution.

  Ask students to compare the results of testing a single straw versus a bundle of straws. Guide them to see how distributing the load changes where and how failure occurs.

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Methods used in this brief

• Experiential Learning