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D. Structures and Mechanisms · Strong and Stable Structures

Strong and Stable Structures: Unit Review

D1.1 D1.2 D2.1 D2.2 D2.3 D2.4 D2.5 D2.6 D2.7 A1.1 A1.2 A1.3 A1.4 A1.5 A3.1 A3.3About 40 minutes
Learning goals
  • I can describe structures by their form and function and sort them as natural or built.
  • I can explain strength and stability and ways to improve them.
  • I can explain forces, loads, struts and ties, and choose materials for a structure.
  • I can assess the effects of animal and human structures on society and the environment.

Words to know

structure
Something with a supporting framework that holds a load.
strength
A structure's ability to support a load.
stability
A structure's ability to keep its shape, keep its balance, float upright and stay in one spot when a force acts on it.
strut
A part that is squeezed (compression).
tie
A part that is stretched (tension).
property
A feature of a material, like strong, light or waterproof.

Let's review!

In this unit you became a structural engineer! You learned what structures are, how form fits function, how forces and loads act on structures, how to make structures strong and stable, what struts and ties do, how to choose materials, how animal and human structures affect the environment, and why strong, stable structures matter to communities. You also designed and built your own tower.

This review has a few questions from every lesson. Try each one, then press Show answer to check.

STRUT: squeezedTIE: stretchedtable legs push back upswing chains pull to hold the seat
Review: a strut is squeezed and pushes back. A tie is stretched and pulls.

What Is a Structure? Natural and Built

1

What is a structure?

2

Sort: a spider's web, a fence, a beaver lodge, a playground slide.

3

What is the load on a bookshelf?

Form and Function: Shaped for the Job

1

What is the difference between form and function?

2

Is an egg a solid, frame or shell structure? A ladder? A brick wall?

3

Why does a camping chair fold?

Forces and Loads on Structures

1

Are the people in a school a dead load or a live load?

2

Is a swing chain in compression or tension?

3

Strong wind tips over a patio umbrella. Did its shape, balance or position change?

Strength: Making Structures Stronger

1

What is strength?

2

Name two ways to make paper stronger.

3

Why are triangles used in bridges and towers?

4

In a fair test of paper bridges, what should change?

Struts and Ties: Push and Pull Parts

1

Is a table leg a strut or a tie?

2

Is a kite string a strut or a tie?

3

Why does one tight string across a square frame stop it from leaning only one way?

wide baseheavy partslowheavyanchor itropes and pegsbalancethe load
Review: four ways to make a structure stable.

Stability: Staying Steady, Balanced and Afloat

1

Name three ways to make a structure more stable.

2

Why should you not stand up in a canoe?

3

Can a structure be strong but not stable? Give an example.

Choosing Materials for Strong and Stable Structures

1

Name three properties builders think about.

2

Why was snow a good material for an Inuit iglu?

3

Why would glass be a poor choice for the road deck of a highway bridge?

Animal Builders and Human Builders: Effects on the Environment

1

Name one helpful and one harmful effect of a beaver dam.

2

How are animal building materials different from most human building materials?

3

Name one way people can build with less harm to animals.

Why Strong and Stable Structures Matter

1

Name two ways strong and stable structures help a community.

2

What is a building code for?

3

Why can a long-lasting structure be better for the environment?

Design Challenge: Build a Strong and Stable Tower

1

Name the steps of the engineering design process.

2

"You may use only 10 straws." Is that a criterion or a constraint?

3

Your tower tips in the wind test. Name one improvement.

Just for fun

Riddle: What has four legs but can never go for a walk?

A table! (Its legs are struts, so they are much too busy holding things up.)

How to use this review

Do one or two sections at a time. Say each answer out loud before you press Show answer. If you miss a question, go back to that lesson and redo its activity: building and testing is the best way to remember. Then try the quiz below.

Check your understanding

Quiz

1.

Which is a natural structure?

2.

A bicycle helmet is a...

3.

The cars on a bridge are a...

4.

Which shape keeps its form best in a frame?

5.

A strut is...

6.

Which makes a structure more stable?

7.

Which property matters most for a tent roof?

8.

A helpful effect of a beaver pond is that it...

9.

A building code helps make sure structures are...

10.

In the design process, what do you do after testing?

For parents and teachers

Use mistakes to choose what to revisit. Each review section matches one lesson.

  • Can't say what a structure is, or sorts natural and built by material instead of maker: revisit What Is a Structure? Natural and Built and redo the structure hunt.
  • Mixes up form and function, or solid, frame and shell: revisit Form and Function: Shaped for the Job.
  • Mixes up dead and live loads, or compression and tension: revisit Forces and Loads on Structures and the forces lab.
  • Can't explain strength or ways to strengthen materials: revisit Strength: Making Structures Stronger and the paper bridge challenge.
  • Mixes up struts and ties: revisit Struts and Ties: Push and Pull Parts and the straw frame lab.
  • Confuses strong with stable, or forgets floating: revisit Stability: Staying Steady, Balanced and Afloat and the tower and boat tests.
  • Names only strength when choosing materials, or can't explain Indigenous material choices: revisit Choosing Materials for Strong and Stable Structures.
  • Sees environmental effects as all good or all bad: revisit Animal Builders and Human Builders: Effects on the Environment.
  • Gives opinions about structures without reasons: revisit Why Strong and Stable Structures Matter and the community structure report.
  • Skips planning or changes many things at once: revisit Design Challenge: Build a Strong and Stable Tower and try it with a new load.

A few mistakes are normal. Praise answers that use unit words (load, strong, stable, strut, tie, property) and give a reason.